Web developers aren’t going to shed many tears for Flash, but as Bruce rightly points out, it led the way for many standards that followed. Flash was the kick up the arse that the web needed.
He also brings up this very important question:
I’m also nervous; one of the central tenets of HTML is to be backwards-compatible and not to break the web. It would be a huge loss if millions of Flash movies become unplayable. How can we preserve this part of our digital heritage?
This is true of the extinction of any format. Perhaps this is an opportunity for us to tackle this problem head on.