May I ask how have you been monetizing Flash up to that point?
I remember reading examples from an e-book on how to build 3D scenes with Flex 3 when I was 17-18 years old. It was a short lived dream of mine to create online video games. Instead, I ended-up making add-ons for PHP-based forums.
During that era Unity had its own web browser plugin and there was at least one Tennis-like game on the miniclip site itself.
I owned and ran a web design agency, but because of my skills in Flash a lot of our "value add" was doing impressive experiences/interactive showcases for our various clients. A lot of it was doing kiosk deployment work, which I think is still done today with Flash sometimes.
And even if it's the same amount, having a sandbox that's harder to escape, holding everything else equal, seems like a win for end-users.
Flash's demise, while it caused me no end of grief back in the day as it was the bulk of my income, was a good thing in the end.