allowing inactive players to hold their houses indefinitely is bad for the glitch's real estate market, it would have to forever expand to accommodate new players. i propose a system to deal with this issue: house elves (or gnome/unicorn/dwarf/dust bunnies/whatever)!
every week you need to feed and/or play with your house creature or it'll get progressively angrier, lashing out by ruining crops and trees, letting out piggies/butterflies/chickens, stealing items, leaving poo that lowers mood until finally after 3 months of neglect, in a fit of rage, it sells your home. items left in the house could be mailed back to the owner.
in reverse, if you feed it, it's favourite food or play with it a lot it might leave you a nice present.