The idea of unlimited instanced housing has been suggested since before housing even existed and the only thing they've done is added more limited housing. Even island sanctuary will (probably) not fit the role of housing as I am betting it will not allow you to: Use the hundreds of pieces of furniture in the game, have airships/subs, allow you to invite people over. If I'm wrong then that'd be great, but I imagine it's just going to be a solo instance where you're just given some bullshit busywork.