There is still a possible, but very difficult and improbable, way out of this. The appropriate legislature can change contract law. This may be difficult if it

There is still a possible, but very difficult and improbable, way out of this. The appropriate legislature can change contract law. This may be difficult if it’s federal law that needs changing, but it’s still possible. If necessary, new judges can be appointed/elected who will decide in the city’s favor. Then they can take a new case to court and have the contract voided.