Allow FCs to purchase their own wards with a high amount of gil so that max of 512 plots and 512 apartments can purchase the plots inside the ward(s)? By doing that, can you allow them to upgrade their interior sizes/furnishing slots and exterior sizes too? - For these plots reduce the prices of the FC Wards. Move out FC houses out of the current wards with full refund and give them the chance to purchase the FC ward instead - having FC main house in the center of Ward map in primary plot section.
As for current housing wards, make them all personal instead. But increase their wards up to 100~200+ to make sure that even one player who owns 8 alts could purchase it if they want to, so that people won't have to complain ever about plots being short or limited. Every time whenever Wards are being full in any server or even sizes are full, the server should recognize it and build a new ward automatically. Whether if it is large/medium. Not everyone is willing to stay small forever.
When player relinquish the land, please give 80-90% portion of the land as resale. To prevent the people from over price selling the land and to avoid violation of Term of Service.
Lastly, if people who are personal wishes to join in FC ward that are not FC members and purchase in the plot - perhaps they can get special permission to build housing in there. Now should these people who are in FC ward wish to leave FC or had special access wishes to move out, they'd be moving to personal ward where it's strictly for non-FC players only to purchase in these wards. They can transfer for free and grab the plots that are available within those 50-200 wards, whether it'd be small,medium or large.