This came up a little more than a year ago. (Don’t be misled by the title of the thread, the first few posts probably address much of your concern.)
Let me add that eventually all of us will “go away sometime in the future.” I believe it was a famous economist who observed that, “In the long run, we’re all dead.”
That said, I don’t think the future of Tinderbox should weigh too heavily on your decision. I’ve been paying for updates for two decades now, and I’m not an academic. I don’t make a living using it. I just love the application.
Drop in on a meetup, share what you hope to achieve with Tinderbox, and I’m confident you can be brought up on step quite readily. It is a robust suite of capabilities that can appear intimidating at first; but you don’t need to master all of it at once, and can become very productive using only a fraction of its potential.