I really do believe that apartments would be sufficient for most players if:

a) Base apartments as we have them now had at least the same item count as a small house: 200. The current limit of 100 on apartment placeables is far too restrictive.

b) Add indoor versions of the garden plots (the biggest being 8 slots) and allow apartments to place one (the same as a small house) so they can crossbreed seeds.

Those two things alone would put apartments close enough to small houses to be more than adequate for most individual players. Obviously this does nothing for Free Companies looking for a house but it might get a few of those "for sale" sign humpers out of the running when competing for a house.

More elaborate things SE could do include:

c) Add bigger sizes of apartments with bigger price tags. This requires more work than the above two things but it certainly seems feasible to implement.

d) Add FC apartments. Again this requires more work than the above two things but doesn't seem out of the realm of possibility.

I know that many people want an "outdoor" instanced area but for whatever reason, SE has some issue with adding instanced, yet outdoor spaces for housing. Until that hurdle is overcome, yards or outdoor balconies for instanced housing/apartments is probably not on the table.