It's been all but inevitable for years now.
The biggest source of flash is videos.
Google has long since made Youtube capable of playing video in pure HTML5. So have many other video sources.
Advertising -- hmphh, those just deserve to
DIEEEE, flash or HTML5.
The last big holdout is apparently flash games, I am not sure why those would be so important, but Mozilla's Shumway project aims to preserve these by delivering an open-source HTML5 reimplementation of the flashplugin.
