Housing shouldn't be limited. If they have the capacity to add districts at any time without impacting stability, then they should procedurally add districts when needed so housing land does not become a limited resource. Having an entire system completely closed off to players is, quite frankly, a waste of those development resources. Again, not because they do not want to put in the time to make money or to go though the process, but because they are hard locked out of it. This is incredibly detrimental to the player experience, and should not be something anyone has to work around. This is not that kind of game.