The timer is already there.
You know how I mentioned my friend above? He's been focused on WoW since the expansion release. While his subscription is still active, he hasn't logged into FFXIV to play since Battle for Azeroth was released. Guess what showed up in my Estate timers yestrday (image taken just before I'm posting this)?
We're absolutely getting into hand-holding territory when someone can't take 10 second to flip through a submenu on their own to look up information about something they presumably care about and they expect someone else to bring that information to their attention instead.
And it would be totally unnecessary if they were simply using their house in the first place as SE intends. If SE didn't care whether or not players were using their houses, there would be no auto-demo timer based on house entry. It would have been tied to active subscription.
Let's stop enabling the hoarders who are wasting limited resources that others would be using if they had the access. Let's start encouraging personal accountability instead.