I think there's definitely a market for some kind of "forever PC". A 20 year old PC is powerful enough to do a lot of stuff, and the really impressive part is that it wouldn't ever need to change significantly. Maybe something like the pico-8 "fantasy console" but for anachronistic "personal computing". Build some minimal apps that aren't user-friendly by today's standards but are nice and simple to program against and have good and simple UI paradigms.