... I guess? The point is more just that you can't know the future, and any constraint like that should have limitations on it, with an upperbound of something

... I guess? The point is more just that you can't know the future, and any constraint like that should have limitations on it, with an upperbound of something like 99 years. That's more than enough time for your kids, grand kids, and even their kids to all enjoy playing baseball in the park, while not saddling your community with your specific vision of outdoor recreation for all time. Like sure, the land donation was no doubt generous and appreciated, and the people involved would have foregone a potential payday had they sold it to a developer to be carved up instead. But on the flipside, it was probably also a big tax writeoff, and the city inherited the unbounded future cost of its maintenance, lost tax revenue, and so on.