So 1, you need an FC to participate (in this system at least)
2, this is an instanced system (one housing instance system per fc, browse fc wards through a directory I guess.)
and 3, you would not be able to participate in the current system AND this system, but this system would probably allow you to have alts with houses.
The hub:
It should cost a pretty penny (I would say more than a top tier large house), and maybe a truckload of fc credits to be able to enter the system, but when you do, you get a sizeable chunk of land where you can place a small house (with a workshop behind it with airships and subs visible).
This is where the process of getting your members their houses starts. The hub area can be built up by depositing materials that can be crafted or bought with gc seals/tomes. (basically play the game and get rewarded with tangible rewards) Upgrading the hub area will alternate increasing workshop size/effeciency, increasing garden size limit/efficiency, house size (From small, to medium, to mansion, to GIGAMANSION making it be the centerpiece of the ward), and (if your FC meets the roster check) opening up the ability to clear away some rubble/brush/stone/what-have-you that is surrounding the hub area so that you can unlock additional, personal, housing plots for the members of the FC.
Maybe have some furnature that can only be used in hub houses like the aetherial wheel, the fc chests and some other buff-giving items so that people will frequent the main building for utility purposes more than just "hey that's some decoration, ok time to go afk elsewhere"
Land unlocking events:
When you get the ability to unlock a plot you will need X amount of people to start "clearing" the area. (Say, get 4 people together to start interacting with the spot, once everyone is ineracting with it, an obstruction is cleared. basically an immersive ready check)
Once the initial clearing has finished an event will start in that area, moving non-participants outside the zone and locking participants inside (think a dungeon wall). This event can be anywhere from a simple guild-hest or FATE level monster encounter where you have to clear a simple monster kill threshold to deem the area safe, to a treasure dungeon boss / eureka NM level of difficulty boss, to something silly like the valentione's event moogle matching game.
Once the event is cleared, a cutscene will play where the FC mammets will rush in and hastilly clear out the remaining blockadges, revealing a fresh area for housing. (during this cutscene the participants will be teleported safely outside the area to avoid any issues with getting stuck, and nonparticipants will see the mammets rushing in and creating a huge dust cloud while the plot(s) load in).
I don't really care how many plots this event would open up lol. It could be one event per plot or per small neighborhood (for this system to work the map has to be fairly modular, so clustering houses into neat neighborhoods is advisable), or it could scale on difficulty where easy kill x of y events would unlock one house, puzzle events could unlock a small cluster, and big bads could unlock the neighborhood, and just have the game pick at (semi) random which unlock severity you'll get. (no wait I like this one. It adds some spice!)
Player houses:
All plots identically sized, can be invested in to progress from small to mansion. (I'd say the yard will grow with the house by clearing some decorative rubble/shrubery/stonework/etc instead of having the decoratable lawnspace shrink as your house grows) Progression line will be cheaper than the hub house, but still pretty costly to give people something to work towards.
Considering population:
This FC ward would probably have to be broken up into separate wards or loading sections to be playable. (god, FCs can be huge) Something like, what, 8 wards (with 8 subdivisions), with 32 housing slots in each? I mean already that's a lot of houses compared to what we have now.. (NO! PIE IN THE SKY! AIN'T NOTHIN' HOLDING ME BACK) I think that should probably be acceptably navigatable through aethernet shards and loading lines at the east (next ward), west (previous ward), north (hub and option to change to subdivision). Especially if we can name the subdivisions.. yeah...
But that's like the biggest of the biggest FCs, I don't think most FCs would need that much space. I'm thinking of the average FC maybe needing 1 ward for everyone who are intent on progressing housing. The demo timer would still be a thing, and maybe you would get the option to... send the plot back to nature.. (to put it nicely) if you don't have enough active members to fill the plot. And since the houses would all have the same options for customization it would probably be really easy to just copy and paste the whole house, interior and all, into a new spot if someone wanted to move their house, so ward cleanup and reorganizing wouldn't be too bad of a hit if you happen to need to condense your population into fewer wards.
Yeah Idk , I REALLY like the idea of being able to literally create a community with my FC and watching things grow as everyone expresses their creativity.