It has been stated that:
So what happens when the leadership wants to remove someone from the FC that currently has a private chamber? Is it still possible to remove someone with a room, and if so does that person lose their furnishings and 300k gil investment?- Vacating Private Chambers
Players must be on free company property in order to vacate their private chambers. Moreover, private chambers must be vacated in order to leave a free company.
I realize that there is much we do not know about private chambers until after the update (such as whether or not the 300k gil must be paid again if you leave your current FC for another), but I think having the details on eviction and expulsion rather than voluntarily leaving is important.