Bingo. I think the "huge share of their former user base" that companies like Affinity are attracting are exactly those casual and semi-pro users who at one time had no option but to go with the 800-lb Adobe gorilla. It's understandable that many of those folks find Adobe's pricing model to be too much, and it's great that they now have more choices. However, those businesses that truly rely on professional creative software as their bread and butter aren't going anywhere, and a few hundred bucks a year is a drop in the bucket for a company that's making money from its creative work.
Let's face it, even before Adobe moved to a subscription model, the company's apps were priced for serious professionals. A standalone copy of the full Adobe CS3 suite used to cost as much as a MacBook Pro.