I don't really like any form of auto demolish or upkeep (even though I do understand the need in the current housing situation), but I definitely like your idea better than what SE is doing atm. I always hated how they force you to stay subbed, if you want to keep your house, even if you know in advance you're not gonna be able to play.
It even encourages people to share their account info (which is prohibited by the Tos too). Imagine I'm going to be out of country for like half a year. I can't take my ps4 with me, what would I do to keep my house? Not only would I be forced to keep paying for a service I can't use, I'd have to ask someone I trust to log in and reset the timer, or lose my house I worked hard for. I wouldn't need to do any of that, if I could just pay in advance.