Player housing already exists in some form in WoW as Garrisons. All they need is to diversify the models and implement a ton of artwork to be spawned inside buildings by players.
We were Loggers in the BfA Battlefronts and they can simply add it as a new gathering profession across all Azeroth wish so many types of vegetation that varies from zone to zone.
Carpenters would just craft plans that can be sold to players for various house and furniture models . Other professions can craft Reagents that would add or change textures, effects, usage etc.
Does it sound like a lot to add to the game ? It shouldn't if they release in 2023.