I doubt the FC wards would fill up even with the switch to personal wards.

I have an alt on Zurvan with a small FC house. Even after the ward switch to personal ward, there's zero new house owners in my ward, which goes to show that most people who want a personal already got one and they would prefer to stay on an original personal ward (19-22) which is well populated rather than switching to a converted ward even if there's still nicer plots available.

Just putting out there that this is such a non-issue I sincerely doubt SE is paying any attention and will allocate resources to (fix? If it even is an issue at all).