I maintain that video is what made Flash ubiquitous, and thus enabled websites to assume that visitors would have Flash installed. HTML5 removes that advantage

I maintain that video is what made Flash ubiquitous, and thus enabled websites to assume that visitors would have Flash installed. HTML5 removes that advantage, so the installed base of Flash will decrease, causing more and more sites to not develop for a Flash-audience. So nominally, the post is right - HTML5 doesn't replace Flash. It renders Flash obsolete. Remember Shockwave? Also a browser-plugin, but only used for small niches, games etc. Never had the ubiquity of Flash. This is where Flash is going after HTML5.