Nice talk, its just what is needed without all the hype.
All I can say is that I'll stick to Silverlight as your talk has made me more of skeptic of HTML5. I just hope your comment at the end about Windows 8 doesn't mean that microsoft has taken resources away from xaml and focused them on HTML5 instead.
I think I'd switch profession before going down the HTML5 path. If I imagine myself doing HTML5 all day for a living, and pulling my hair out testing all the variances on 10 versions, having to look at a matrix on the web for which simple little feature works in which versions of each browser, I think it would be a dream to just think 'please give me an environment with 1 spec and 1 implementor that moves fast and works the same even with IE6 on NT', we do have that today with Silverlight.
Clearly apps on mobile are winning against web, I think once the hype moves from HTML5 the focus will be back to apps.