Yeah I wouldn't draw attention to the concept of software longevity anywhere. New SAAS by a solo developer is not what I think of when I think of things that will last.

OP you're just straight up not going to get people for who stability is a priority any time soon. Your target market is people who like to fiddle with their work tools, likely beyond pragmatism and in to productivity as a hobby territory. Guy that wants to get his organisation on to something and know he wont have to think about it again, ie the guy who cares about "built to last", is going to go Salesforce and call it a day.