The real solution to this would be to just give everyone an upgradeable housing plot. The only reason that houses cost anything at all is so that SE does not have to invest the resources necessary for everyone to have a house. WoW and Wildstar have both made this investment, despite Wildstar faring far poorer than FFXIV financially so far(they are going f2p soon).

If they add more wards, people with money will just buy up all the plots again. I know several people who have multiple houses for just their characters.

If the aim of housing was to sink gil out of circulation, then that cost could be shifted to upgrades for said plots.