I read the article one more time, it does seem to be much more lucid now. I'll attribute my bad interpretation of it on the fact I read it very late last night - when it seemed to me he was saying that HTML5+JS was replacing .NET and WPF.
He still makes some absurd claims though:
"... they were told that all their experience, all their knowledge, and every program they have written in the past would be useless on Windows 8"
I was a Win32/COM/MFC developer at the time Microsoft announced .Net. The joke at the MS Dev Conference at the time was that everybody in the room just had their salary drop 20%.
Perhaps the only reason a shift in Win app development tooling isn't such a big deal today is simply that MS does not have the clout that they did back then. Windows 8? Seriously, it's many years off before anybody (including MS) going to try to make a profit on a shrinkwrapped app that doesn't run on Windows XP.
But there are nevertheless a great many developers who've hitched their wagon to MS as a career path. They're understandably antsy as they watch all the hot demand go for iPhone/Android/tablet development. This would explain a lot of the angst I think.
He was saying, I think, that that was the public perception. I'm pretty confident, though I obviously don't speak for him, that that's not his own opinion. At the end of the article, he seems to make that clear.
He still makes some absurd claims though:
"... they were told that all their experience, all their knowledge, and every program they have written in the past would be useless on Windows 8"
Flamebait. FUD. Just look at the comments there.