I've got no stake in this, but I'll note that from the claims Wolfram has made, they've got a 30 year track record in which notebooks going back to 1.0 still run in the latest version.
But does your version 1.0 you purchased still run? Or have you been forced to upgrade over the years?
I don’t think being forced to upgrade is as much of a concern as receiving incompatible upgrades, or not receiving anything at all. Remember, Wolfram is trying to reach industry here, not just individual software developers.