Just make personal Housing instanced. Like both Wildstar and Everquest 2 do.
- There's a new MMO and a very old MMO - both having found a working solution. Compare them to see how a decade changes the concept, but keeps the basic notion in tact.
Instanced housing means you can have an unlimited number of them - and set them up to have whatever thematic designs are desired.
There are plenty of spots in all three of the cities that I could imagine one 'turning down an alley' to zone into their personal instance.
The Gridanian ones could be tree houses or clearing in a wooded area with a little stream by them.
The Limsa ones could be houseboats or lighthouse-like towers.
The Uldan ones could be back alley slums or towering minarets with a view of the city and desert below.
- And all of this could be tied to a quest one does somewhere between the level 15 'leave town' quest and the later 'pick a grand company' quest. With a fee to buy the house you plop on it, move it, etc. Players who already have personal houses could get some level of gil refund, and a special 'early buy in' house design only they get - as compensation for what they had to pay beforehand.
But whatever the specifics. Make it instanced individually. If we MUST have neighborhoods... take a page from the Sims and from what Wildstar is about to do... and let up to [x] people band together and put their plots into a neighborhood instance - with the ability to vote someone off the neighborhood (throwing the evicted person back to an individual instanced plot)... And these two, could be spun off in unlimited numbers based on demand.
Why they chose public access uninstanced for the housing, in a modern MMO... where we have long since learned why doing uninstanced personal content is a bad idea... I don't get. One only has to look at the history of why WoW started the instanced dungeon concept to know this... It was to solve the very people we see here in housing, that was killing Everquest's uninstanced Dungeons - too many people and not enough content leading to areas being unusable by paying subscribers. So WoW made instanced dungeons, and got to 11 million players, while Everquest at its height had maybe 100,000 to 300,000....
The limited instancing, as open zones, nature of housing in this game is going to kill housing - and the problem will get increasingly bad as the player population grows.