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GitHubBrainstorming Stadium Public Equity Models
The strongest version of the idea is not simply “if taxpayers pay, give them cheaper tickets.” It is:
Public money should enter a stadium deal as capital, and capital should receive a contractual return. That return can then be deliberately converted into public access.
That is quite different from the prevailing subsidy model.
The reporting you linked makes the asymmetry unusually clear. The Miami Marlins ballpark was described as a roughly $500 million project, with about $350 million supplied by Miami-Dade County and the City of Miami; the financing structure ultimately pushed the taxpayer cost above $2 billion. The interview also discusses free or discounted land, tax exemptions, and other benefits that often do not even appear in the headline construction subsidy. ^1
The striking passage around 14:20 is even more relevant to your question: former Marlins president David Samson says that in making the deal he was competing against other teams and owners, not thinking about Miami residents; when asked whether the public came up in the negotiations, he says essentially that they did not. ^1
That is a governance problem as much as a financing problem.
1. What would “proportional equity” actually mean?
Start with a conventional private investment.
If:
- stadium construction = $500 million
- public capital = $350 million
- private capital = $150 million
then the capital structure is approximately:
| Investor | Capital | Share of project capital |
|---|---|---|
| Public | $350M | 70% |
| Team/owners | $150M | 30% |
| Total | $500M | 100% |
If this were a hotel, apartment project, shopping center, power plant, or ordinary joint venture, nobody would find it peculiar for the investor contributing 70% of the capital to demand substantial economic rights.
Forbes now lists loanDepot park's construction cost as $516 million, capacity as 37,446, and Miami-Dade County as the venue owner. Using $516 million instead gives the original $350 million public contribution an approximately 67.8% capital share. ^2
But there is an important distinction:
owning the stadium structure is not the same thing as owning the economic upside generated by the stadium.
A municipality can technically own the building while the team gets most of the valuable cash flows: ticketing, sponsorships, naming rights, premium seating, media-related economics, concessions, parking, and appreciation in franchise value.
That is exactly where I would change the model.
2. A “Public Capital Rule”
A fairly simple statute could say:
Every dollar of public stadium assistance must be classified as one of three things:
- a loan,
- an equity investment,
- or a purchase of specifically enumerated public benefits.
No fourth category called “subsidy.”
And importantly, “public contribution” would include fair-market-value land, property-tax exemptions, sales-tax exemptions, infrastructure built primarily for the stadium, below-market financing and the present value of other foregone government revenue.
The TED discussion explicitly identifies land and tax exemptions as forms of subsidy that should be counted. ^1
That closes one of the easiest accounting loopholes.
3. What could taxpayers receive?
There are several ways to structure the consideration, and I would probably combine them rather than select only one.
| Model | Public receives | Main advantage | Access effect |
|---|---|---|---|
| Pro-rata stadium equity | Ownership equal to public capital share | Closest to normal investment practice | Dividends fund access |
| Preferred public equity | Capital returned first + fixed return | Predictable; team retains upside afterward | Dedicated annual access fund |
| Gross-revenue royalty | 3–10% of designated revenues | Harder to eliminate through accounting | Excellent recurring ticket funding |
| Profit participation | Share of operating profit | Aligns interests | More volatile |
| Appreciation warrant | % of increase when franchise is sold | Captures subsidy-created franchise value | Potential huge long-run payoff |
| Public-seat covenant | 5–20% of seats at controlled prices | Directly addresses affordability | Immediate |
| Ground lease | Market rent for public land | Prevents free-land giveaway | Funds community benefits |
| Community benefit trust | Revenue paid into independent trust | Insulates benefit from annual politics | Tickets, transit, youth sports |
| Naming/concession share | % of ancillary stadium income | Monetizes public asset | Can subsidize food/tickets |
| Clawback | Subsidy repayment if team leaves/sells | Prevents privatized windfalls | Protects taxpayers |
The important part is that cheap tickets need not be charity paid for by the team.
They can be the dividend paid on the public's investment.
That is a very different political and economic framing.
4. The Miami experiment
We can put some current numbers around this.
Forbes estimates that the Marlins generated approximately $320 million in 2025 revenue, with about $53 million in operating income. It estimates the franchise itself at roughly $1.5 billion in 2026. ^2
Those figures let us model several hypothetical versions of your proposal.
Illustrative annual public return
| Arrangement | Approx. annual public value |
|---|---|
| 5% of $320M revenue | $16.0M |
| 10% of $320M revenue | $32.0M |
| Repay $350M over 30 years at 5% | $22.8M/year |
| 70% of $53M operating income* | $37.1M |
| 10% seat allotment sold for $20 instead of $45 | $7.6M implicit annual benefit |
*The 70%-of-profit scenario is useful for illustrating proportionality, but I would not recommend giving government 70% of an MLB franchise's voting equity merely because it helped build the stadium. The cleaner asset is a stadium operating company or contractual revenue interest.
Forbes currently estimates an average Marlins ticket price of approximately $45. ^2
Here is the modeled comparison:
Download the graph
There is a revealing result here.
If taxpayers merely received enough annual value to amortize their original $350 million investment over 30 years at 5%, that would be about:
$22.8 million per year.
At a $40 subsidy per admission, that buys roughly:
569,000 subsidized admissions every season.
Miami drew about 1.16 million fans in 2025, averaging only 14,282 per game in a stadium holding roughly 37,442. ^3
So in Miami specifically, the constraint isn't even stadium capacity.
There were, on average, roughly 23,000 unused seats per game.
That creates an enormous opportunity for a public-access program whose marginal cost could be very low.
5. The better idea may be seats rather than cash
This is where your access objective changes the optimal policy.
Suppose a community contributes 30% of stadium value.
Instead of demanding 30% of the team's profits, it could demand something like:
10% of ordinary seating inventory must remain Public Benefit Inventory for the duration of the public investment.
At loanDepot park:
37,442 seats × 81 games × 10%
≈ 303,000 public tickets per season.
A 15% requirement becomes about:
455,000 tickets.
A 20% requirement becomes about:
607,000 tickets.
And that doesn't mean free tickets.
It might mean:
The Community Seat
A municipality could establish a permanent ticket class priced according to local income rather than market-clearing price:
| Household qualification | Ticket price |
|---|---|
| Medicaid/SNAP/other income-qualified | $5 |
| Under 200% FPL | $10 |
| 200–300% FPL | $15 |
| Local students/youth teams | $5–10 |
| General county resident lottery | $20–25 |
| Normal commercial inventory | Market price |
That accomplishes something revenue sharing alone doesn't:
it guarantees that poorer residents physically remain part of the crowd.
That matters because otherwise stadium economics naturally tends toward segmentation: suites, clubs, premium seats and higher-income consumers increasingly dominate because they produce more revenue per seat.
6. I would make the benefit proportional—but not literally identical to equity
There is a legitimate counterargument to “70% public financing = 70% of the team.”
The private owners also contribute things that aren't stadium construction capital:
- ownership of the franchise
- league membership
- player contracts
- management
- intellectual property
- operating risk
- broadcasting relationships
- preexisting franchise value.
So taxpayers financing 70% of a stadium does not logically mean they bought 70% of the Miami Marlins.
But it very reasonably means taxpayers bought 70% of the stadium project.
The public's claim should therefore attach primarily to the incremental economics created by that project.
For example:
StadiumCo
Create a separate legal entity:
Miami Ballpark Operating Co.
Its capitalization might have been:
- Public: $350M — 70%
- Marlins: $150M — 30%
StadiumCo receives:
- stadium rent
- parking
- concessions
- naming-rights payments
- premium-seat revenue attributable to the facility
- non-baseball event rentals
- advertising inside the facility
- development income on stadium property.
Baseball operations remain privately owned.
That is much cleaner.
7. The public could hold preferred shares instead
This may be politically easier.
Rather than permanent 70% ownership:
Taxpayers receive $350 million of preferred equity carrying a 5% return, redeemable over 30 years.
That produces the roughly $22.8 million annual capital recovery modeled above.
Once taxpayers have received:
- their $350M principal,
- plus agreed investment return,
the preferred shares disappear.
The team gets complete economics afterward.
That is not anti-business. In fact, it closely resembles conventional project finance.
It simply asks:
Why should governments accept investment terms that no private investor would?
8. My favorite addition: an appreciation warrant
This addresses something conventional stadium deals miss almost completely.
A new stadium often makes the franchise itself more valuable.
So if public investment enables that appreciation, the public could receive a small warrant.
For example:
Public receives 15% of franchise appreciation attributable to a future sale, after adjusting for subsequent private investment.
Imagine:
- team worth $1.0B when stadium deal closes
- later sold for $2.0B
- appreciation = $1.0B
- public participation = 15%
Community receives:
$150 million.
The owner still receives $850 million of appreciation.
This mechanism is especially defensible when an owner gets a major publicly financed facility and then sells the franchise shortly afterward.
It prevents:
public investment → private capital gain → immediate exit
without compensation.
9. Revenue sharing may actually be better than profit sharing
I would strongly favor gross revenue over accounting profit.
Suppose the agreement says taxpayers receive 10% of profit.
A sophisticated company can legitimately make reported profit surprisingly small through:
- management fees
- related-party leases
- depreciation
- interest
- affiliated-company payments
- executive compensation
- capital charges.
Gross revenue is much harder to manipulate.
Something like:
5% of all stadium-derived gross revenue until taxpayers achieve a specified investment return.
would be administratively simpler.
And even 5% of the Marlins' current approximately $320M overall revenue would be about $16M annually, although an actual agreement should apply its percentage only to carefully defined revenue streams. ^2
10. Then earmark the return for access
This is critical.
If the $20 million simply disappears into the municipal general fund, you've fixed the financial inequity but not necessarily the sports-access inequality that motivated your question.
I would establish an independent:
Community Sports Access Trust
Every dollar of stadium return could be divided approximately:
| Use | Share |
|---|---|
| Affordable game tickets | 45% |
| Youth sports/leagues/equipment | 20% |
| Free transit to games | 10% |
| Accessible seating / disability support | 5% |
| Community recreation facilities | 10% |
| Reserve/endowment | 10% |
That turns professional sports into a funding mechanism for broader participation in sport.
11. Tickets aren't the only affordability problem
A "$15 ticket" is not really $15 if attending requires:
- $40 parking
- $14 beer
- $9 soda
- $12 food
- ticketing fees
- transportation
- several hours of childcare.
So a serious public-benefit agreement should specify a complete affordable game-day product.
For example:
Community Game Pass — $25
Includes:
- admission
- round-trip public transit
- one basic meal
- no service fee
- no resale
- no dynamic pricing.
A parent and two children could attend for $75 total, rather than an outing easily running into several hundred dollars.
That is much closer to the accessibility issue you're getting at.
12. Don't means-test everything
There is also a cultural problem with making inexpensive access exclusively a poverty program.
I'd divide public inventory into perhaps:
- 50% income-qualified
- 25% youth/school/community organization
- 25% resident lottery open to everyone
That gives working- and middle-class residents access too.
It also makes the program politically durable because the public benefit isn't confined to a narrowly defined population.
13. One especially clever mechanism: unused-seat conversion
Miami demonstrates why this could work extraordinarily well.
In 2025 the Marlins averaged about 14,282 attendance in a roughly 37,442-seat stadium. ^3
So the contract could contain:
72 hours before first pitch, a percentage of unsold inventory automatically converts to Community Inventory.
For example:
- Team sells normally.
- Three days before game, unsold seats enter community pool.
- Qualified residents buy them for $5–15.
- 12 hours before first pitch, remaining community seats become available to any county resident for $10–20.
- Tickets are mobile, identity-bound and non-transferable to discourage scalpers.
Economically, this is compelling.
The marginal cost of putting someone into an otherwise empty seat is tiny, while that person may:
- buy food,
- use transit,
- become a long-term fan,
- bring children,
- participate in civic culture.
It converts perishable inventory into public benefit.
14. A model stadium deal I would actually recommend
If a team proposed a $1 billion stadium with a $400 million public contribution, I would structure the public portion approximately like this:
| Provision | Requirement |
|---|---|
| Public capital | $400M |
| StadiumCo economic interest | 40% |
| Preferred return | 4–5% |
| Maximum recovery period | 30 years |
| Minimum public seats | 10% |
| Unsold-seat conversion | Begins 72 hours before event |
| Community ticket cap | ~$20 in today's dollars |
| Ticket fees | $0 |
| Transit | Included on community tickets |
| Concessions | Basic affordable meal requirement |
| Franchise-sale warrant | 10–15% of attributable appreciation |
| Public land | Market-value ground lease |
| Naming rights | Proportional StadiumCo revenue |
| Parking | Proportional StadiumCo revenue |
| Team relocation | Immediate accelerated repayment |
| Financial disclosure | Annual audited statement |
| Community trust | Receives all public distributions |
| Sunset | Equity redeemed once required return achieved |
That still allows the private team to make enormous amounts of money.
It simply changes the government's position from:
subsidizer
to
investor representing residents.
Why I think this is economically defensible
The academic literature makes the conventional justification for subsidies difficult to defend. Reviews of stadium economics find little evidence that stadiums are meaningful engines of metropolitan economic development, and recent scholarship concludes that typical public funding substantially exceeds economically justified levels. ^4
An older Brookings synthesis similarly concluded that teams and stadiums generally do not generate significant local economic growth or employment sufficient to justify the subsidies. ^5
So if a community chooses to finance one anyway, the justification is better understood as:
“We value professional sports as a civic amenity.”
And once you say that, your accessibility argument becomes much stronger.
If taxpayers are buying a civic amenity, residents—rather than merely the highest bidders—should actually be able to use it.
Public libraries don't charge the highest price the market will bear for entry. Parks aren't auctioned every Saturday to the wealthiest residents. A publicly financed stadium is obviously different because professional sport is a commercial enterprise, but the same principle doesn't have to disappear completely.
The policy compromise could be:
Most seats remain market-priced. A meaningful minority of capacity becomes the public dividend for the capital taxpayers supplied.
That strikes me as much more defensible than either fully socializing professional sports or continuing to socialize stadium costs while privatizing essentially all of the upside.
You said
In response to 6. Stadium ownership equity is not equal to team franchise: in order to get a baseline, what is the net present value of the Miami Marlins?
ChatGPT said
Yes. This distinction changes the analysis substantially.
There are actually three different numbers we should keep separate:
- Value of loanDepot park as real property
- Enterprise value of the Miami Marlins franchise
- Equity value of the Marlins after subtracting net debt
Forbes' March 2026 estimate gives us a good baseline for #2.
Current Marlins enterprise value: ≈ $1.5 billion
Forbes values the Miami Marlins at $1.5 billion as of March 2026, versus $1.05–$1.1 billion in 2025. Sportico independently comes in very close at $1.45 billion. ^2
Importantly, Forbes explicitly defines this as enterprise value:
equity + net debt
and says the valuation includes the economics the team derives from its stadium agreement, but does not include the stadium real estate itself. ^6
That is almost exactly the distinction we need.
| Asset | Approximate current value | Owner |
|---|---|---|
| Marlins franchise EV | $1.50B | Sherman ownership group |
| loanDepot park real estate | Separate asset | Miami-Dade County |
| Stadium county book value (2024) | $387.2M | Miami-Dade County |
| Original stadium construction capitalized by county | $514.7M | Miami-Dade County |
Miami-Dade's own financial statements report the stadium at a $387.2 million depreciated carrying value as of September 2024. ^7
So my previous suggestion of giving the public equity in “StadiumCo” doesn't entirely solve the problem: Miami-Dade already owns the stadium.
The more interesting question is exactly the one you're getting at: what was the economic value of the franchise that benefited from the public investment?
But “net present value” needs a little refinement
$1.5B is today's estimated enterprise market value, not technically a DCF-derived NPV.
If we want the public-finance analysis to be rigorous, I would use $1.5B as the observable terminal/current market value, and separately construct an NPV/DCF from the franchise's expected cash flows.
Forbes estimates:
- Revenue: $320M
- EBITDA-like operating income: $53M
- Enterprise value: $1.50B
That means the market is currently valuing the Marlins at roughly:
4.7× revenue
28.3× operating income
The $53M is EBITDA rather than free cash flow, so simply capitalizing $53M would overstate distributable cash. But franchise values also incorporate extraordinarily valuable MLB rights, scarcity value, national media economics and expected appreciation. Forbes explicitly says its methodology considers historical transactions and the future economics of the sport. ^6
The 2017 transaction gives us an even better anchor
Bruce Sherman/Derek Jeter's ownership group actually purchased the Marlins for $1.2 billion in 2017. The acquisition was reportedly financed with approximately:
- $800M common equity
- $76M preferred equity
- $400M debt.
That transaction occurred only five years after the publicly financed stadium opened.
And this is where the public-equity argument becomes considerably more interesting.
Suppose we conceptually divide the assets:
Public: owns the ~$515M ballpark.
Private owners: own a baseball franchise currently worth ~$1.5B whose value includes the favorable economics of playing in that publicly financed ballpark.
Forbes explicitly says its $1.5B valuation includes the economics of the stadium deal but excludes the stadium real estate itself. ^6
So these aren't overlapping $1.5B and $515M valuations. They're substantially different economic assets.
What was the franchise worth when taxpayers made the investment?
This is probably the baseline we actually want.
The stadium agreement was approved around 2009 and the stadium opened in 2012. The Sherman group subsequently paid $1.2B for the franchise in 2017. ^8
Rather than asking:
“What percentage of the stadium should taxpayers own?”
I think the next model should ask:
How much incremental franchise value was created or protected by the publicly financed stadium, and what would the public's investment have been worth if taxpayers had received equity-like consideration for supplying that capital?
That is a much stronger counterfactual.
For example, suppose—purely illustratively—that the Marlins were worth $400M immediately before the stadium agreement, and the public supplied approximately $350M toward the stadium.
It would not follow that taxpayers deserve 350 / (400+350) = 46.7% of the franchise, because the $350M bought a separate physical asset.
But if an independent appraisal determined that the new stadium increased the franchise's NPV from $400M to, say, $700M, then the public investment generated approximately:
$300M of private franchise-value uplift.
A defensible agreement might therefore give taxpayers a claim against some portion of that incremental $300M, rather than ownership of the entire franchise.
And we have an unusually interesting natural experiment here because the franchise actually sold for $1.2B five years after the stadium opened.
There was even a primitive version of precisely this idea in the real Marlins agreement: Miami-Dade had negotiated a right to 5% of certain profits from a franchise sale within ten years. When Loria sold for $1.2B, a dispute arose because he claimed allowable expenses meant there was no qualifying net profit to share. ^9
That episode strongly suggests one improvement to our hypothetical policy:
Never base the public's return on owner-defined “net profit.”
Use either gross sale proceeds, independently appraised appreciation, or a predetermined equity/warrant formula.
One other number changes the picture dramatically
The public's relevant investment may not really be $350M.
Miami's stadium debt is still outstanding, and recent reporting says total county bond repayments alone are expected to approach $2.7 billion through 2049, including roughly $1.2B repayment on one ~$80M financing tranche and roughly $1.3B on $319.2M of other bonds. ^10
That means we have an intriguing situation today:
Marlins franchise EV: ~$1.50B
County stadium debt repayment: ~$2.7B over its life
Stadium real-estate book value: ~$387M
Team: privately owned
Stadium: publicly owned
So I would not say “the public contributed 70%, therefore it should own 70% of the Marlins.” That conflates the two assets.
I would instead construct a counterfactual NPV model at the date of the stadium agreement:
Marlins franchise value without new stadium
versus
Marlins franchise value with publicly financed stadium
Then we can calculate what percentage of the incremental franchise value was attributable to taxpayers.
That is likely the most economically defensible basis for determining what an equity warrant, revenue participation, or community-access dividend should have been.
And because we know the eventual 2017 sale price ($1.2B) and today's estimated EV ($1.5B), we have unusually good endpoints with which to test the model. ^2
If you want to continue this quantitatively, the next step should be to reconstruct the Marlins' approximate 2008–2012 franchise NPV both with and without the stadium deal, then calculate the taxpayer-attributable value creation. That would give us a much less arbitrary answer to “what percentage should the public have received?” than simply dividing construction costs.
You said
You are absolutely right, although I think without even diving in so far, a public contract could probably be satisfied with a modicum of goodwill, such as 20% of seating reserved for lottery-based affordable pricing (e.g. ~$50/ticket). The problem of municipal tax subsidy exploitation will persist until addressesing the real public policy issue that makes this all possible: the leverage the team has by being able to move. Spitballing: a lot of public/private social constructs like these aren't worth the paper they're written on because of the incredible leverage the companies, teams, etc. (insert behemoth investment), and while the communities trying to attract these investments (in this case, a sports team) they often engage in a race to the bottom in terms of what they're willing to subjugate tax payers to in service of the large private entity (see: Amazon HQ #2 fiasco circa ~2019). What would a public policy look like that involved cities working together across the nation to have some sort of bulwark against this leverage? Provide 3 brief ideas, scoring each one, and we'll go from there. Be sure to include the regulating body / jurisdiction that would oversee the solution.
ChatGPT said
Yes. I think you've identified the underlying market failure more precisely: the subsidy is the symptom; interjurisdictional competition is the mechanism that gives the private party its bargaining power. Amazon HQ2 illustrated this outside sports particularly well: jurisdictions competed partly on how large an incentive package they could legally assemble. ^11
Three approaches seem worth developing:
| Proposal | Regulating body / jurisdiction | Effectiveness | Political feasibility | Legal durability | Overall |
|---|---|---|---|---|---|
| 1. Interstate “No-Poaching” Compact | Interstate compact commission; states opt in; ideally Congress consents | 9/10 | 7/10 | 8/10 | 8.0/10 |
| 2. Federal Subsidy Floor / State-Aid Law | Congress + Treasury/Commerce | 10/10 | 4/10 | 9/10 | 7.7/10 |
| 3. League Relocation + Subsidy Clearinghouse | Federal Trade Commission/DOJ under new federal statute | 8/10 | 6/10 | 8/10 | 7.3/10 |
1. Interstate “No-Poaching” Compact — 8.0/10
States voluntarily agree that their states and municipalities will not bid against another member jurisdiction using subsidies to relocate an existing major employer or sports franchise. They could still compete on infrastructure, workforce, quality of life, market size, etc.; they just couldn't say, essentially, Miami offered $600M, so we'll offer $800M.
This isn't hypothetical. Kansas and Missouri did essentially this in 2019 after spending years subsidizing companies to move a few miles across the Kansas City state line. Their agreement restricted state incentives for cross-border relocations without genuine job creation. ^12 Ironically, the Chiefs/Royals stadium fight subsequently demonstrated both the idea's value and its weakness: Kansas devised stadium financing that reopened the bidding war. ^13
I would therefore make ours a formal congressionally approved interstate compact, with a permanent commission and enforceable definitions of subsidy rather than a governors' handshake. Congressional consent can elevate an interstate compact into federal law, making it considerably harder for one legislature to quietly evade. ^14
This is my favorite starting point because cities collectively regain bargaining power:
“You're free to move. But none of us will pay you merely to move from one of us to another.”
A team can credibly threaten relocation. It can no longer credibly threaten an auction.
2. Federal “State Aid” Law — 7.7/10
Congress could instead establish national rules governing selective state/local subsidies to large private enterprises engaged in interstate commerce.
For example, public support exceeding $100M might be permitted only when an independent analysis demonstrates public benefit, with mandatory clawbacks and perhaps requirements such as public equity/revenue participation or affordable public access. Pure relocation subsidies could simply be prohibited.
There's an interesting precedent outside America: the EU State Aid regime. EU law generally restricts member governments from selectively subsidizing particular companies where doing so distorts competition and trade, with defined exceptions and review procedures. Professional sports infrastructure is specifically subject to those rules. ^15
A U.S. analogue could effectively tell Miami, Nashville, Seattle, Kansas City and everyone else:
You may subsidize legitimate public infrastructure. You cannot transfer $800M to a private company merely because another American city offered $700M.
This is probably the most economically effective solution because there is nowhere domestically to defect to. Its weakness is political: Congress would be telling governors and mayors that they cannot deploy one of their favorite economic-development tools.
3. Federal Relocation/Subsidy Clearinghouse — 7.3/10
This is the softer and perhaps politically interesting compromise.
Congress establishes an independent Interstate Development Competition Commission, perhaps administered alongside FTC/DOJ competition policy. Any large corporation or professional franchise seeking more than, say, $100M in public assistance must disclose every competing public offer before accepting one.
The commission doesn't necessarily prohibit the subsidy. Instead, it establishes rules of the auction:
public bids → public disclosure → standardized NPV calculation → independent cost-benefit analysis → minimum public consideration → binding clawback.
The particularly useful provision for sports would be a relocation compensation rule. If Team A uses a threatened relocation to obtain $600M from City B, some predetermined fraction of the subsidy or franchise appreciation could become payable to the community it leaves.
That changes the payoff matrix. Relocation remains possible, but threatening relocation ceases to be a costless negotiating weapon.
The distinction I'd make between #1 and #2 is consequential.
#1 is collective bargaining by governments.
#2 is regulation of the subsidy market itself.
I lean toward a hybrid: an interstate compact initially, with standing congressional consent and a federal statutory backstop. That preserves substantial state/local autonomy while solving the prisoner's-dilemma problem you identified. The Kansas–Missouri experiment provides a remarkably good miniature case study: cooperation reduced the incentive war, while loopholes and the possibility of defection eventually threatened to restart it. ^16
And your 20% affordable-seat requirement fits neatly after this reform. Once cities aren't terrified that demanding reasonable public consideration will cause the team to run to the next bidder, Miami can credibly say: “Our standard stadium-investment terms include 20% community inventory at capped prices. Atlanta, Tampa, Phoenix and everyone else in the compact uses essentially the same terms.”
At that point the negotiating leverage has fundamentally changed.
