If I recall, adobe isn't eliminating flash right away. I read somewhere that it was like, they were still supporting current platforms until 2015 or something like that. By then people will be on Windows 10.3, mac OS X house cat, and running Super Debian.
Now, that site could easily be wrong. I think HTML5 is gonna kick it into high gear. MS has what, somewhere around 90% desktop market share, we can assume that say, half of them use IE (probably more), so that's 45%, and out of that percent, probably quite a large number of people who are used to having flash video. I'd guess that those sites will be like, "Hey, check it out, HTML5 has videos!!!".
I made up all those stats, its 2am.