I dont think so. All the big sites are converting to HTML5 now since the highest paying audience is on the iPad. New features will be targeted to that market first as well.
The flash audience will be second class citizens. But with users needing only to change their browsers for a better experience, I think they will do so surprisingly quickly.
OH YEAH!! Because users are renowned for updating their browsers. Flash has 99% of the market. I would gather that 90% of users on the internet don't have a friggin' clue what this whole debate is about and wont care how they view their videos. I like the idea of HTML5, but if it takes off like many preach, users will probably notice how everything is a little less polished and a little more crappy. Then they'll still not care.
The flash audience will be second class citizens. But with users needing only to change their browsers for a better experience, I think they will do so surprisingly quickly.