What technologies are you talking about in particular? I have been working with Microsoft technologies for 6 years or so, so by your estimation I should have had to relearn everything twice now, but I'm still able to write things with C#, Winforms, ASP.NET etc just as I was 6 years ago.

Keep in mind the headline is sensationalist, the article itself says that Silverlight code is easily run as an actual Metro application. It's just to get it in the browser, you'll need to switch to 'full' desktop mode.