Well how about a .05 to .15 cents increase in subscription fee. At the moment FFXIV has an estimated 748,912 active players worldwide, so an increase of .05 to 15 cents would earn SE an additional minimum amount of 35,000 USD monthly, hopefully enough to expand server capacity for housing to be readilly available for all players.

Data for estimate number of FFXIV players from this website: https://ffxivcensus.com