I've read a fair bit about how, over time, there'd be expansions of apartments in the game once all of the wards are filled.
Per a Game Watch interview:
It's been months since the release of apartments and I haven't found any updates on when this will be implemented to allow for people on dense servers to get their housing fix. I've gone through every ward regularly seeking a vacancy from those transferring or deleting, but to no avail.With the implementation of apartments, the personal demands for housing will be 100% met. Each ward has 1 apartment with 90 rooms, and we are ready to increase the number of rooms whenever we want. We designed it so 1 ward can have over 500 rooms per apartment, so it will definitely be able to cover every player.
I realize it's likely a bit lower on the priority because so few servers appear to suffer this, but I would love to get an idea on when this feature is going to be added or where to look for said information.