The idea of allowing all your chars on your account to use one house would be nice. Barring that change, players should still be able to buy housing on an alt if they are really into it.

As for housing, they should have an option to give up your house, receive the purchase price back. You don't lose your gil, that way if you plan on a long break or other such things. SE now has the plot and can set a random timer as to when the plot will go back up for sale so you can't sell it to one person. It gives everyone a shot at it. If a house is lost to the 45 day demolish timer, same applies and random timer for when it goes up for sale by SE. This prevents a player from selling a house to a person by just not entering the house for 45 days and knowing very close to when the buyer would have to be there to buy the plot.

This is not perfect by any means but it would create a more fair system and prevent players from selling to others. As it would only allow for housing to go back to SE and no one else.

As for high population servers. If housing is that big of an issue, transfer servers. Maybe SE could help out with free transfers to servers with “X” amount of open housing plots. With cross server PF and the other cross server chat plans SE has talked about this shouldn't be the big issue it use to be with losing touch with all your friends.