I have played Ultima online for years and enjoyed the player housing but did not enjoy how the landscape was packed with houses and artwork that lagged up the game.
A good idea, if anyone has ever tried Toontown online, is that your player can teleport to a peice of land (stored locally on your hard drive) and on this piece of reserved land you could build your houses or houses, even decorate outside with plants. You could do whatever you wanted on this piece of land, invite friends, guild, even have low level animals walking about, purchase addons like stable master, innkeeper, banker etc.
You could use a housestone or hearthstone to travel to and from your house.
Homes should be a money sink as well, not given from the start.
If this would be done right it could avoid houses taking up landscape or having to build a new map for player housing, just a small island, or perhaps guilds could purchase a bigger plot of land surrounded by mountains / rivers.
Just an idea.
Just one thought that I wanted to add. If player Housing comes into exsistance. I hope that they modify the Professions. Just imagine, engineers making sinks or plumbing. Leather workers making sofas and chairs. Tailors making currtains. Herbalists creating a herb garden that grows herbs but the garden refreshes once a week. Black smiths creating tools for the house. Enchanting could create lustrious glows or auras for items in the house and of coarse. Jewelry crafting making little gem base bobbles for the house.
If they go with player housing it would be a good idea to use the professions for housing items.
Shadow bane had a very good version of this also.
I really hope WoW does implement this in the upcoming expansion.
Only time will tell!