This is just the development PR machine trying to drum up interest in the next new shiny bits. It doesn't mean the old stuff is lost, it just means that the excitable evangelists won't be talking about it.
And that's exactly what customer (whom we write software for) listen & respond to. How are you supposed to sell a customer on developing their app in Silverlight/WPF when Microsoft made it pretty clear Silverlight/WPF is now legacy like Winforms?
They could have sold the shiny new desktop that was comprised of Silverlight but no windev went "not invented here" on us, thre shiny on it, and Ballmer bought it hook, line, and sinker.
WK's got it spot on. Economically it screws things up for us devs. What do will do until next year? Oh that's right convince our customers who just spent boatloads on a Silverlight/WPF app still in incubation that "it's ok... your app will still run on Windows 8". For new projects what do we tell them? Well XAML is kinda like HTML5...
One other piece I don't hear people talking about is the vast loss of open source code and published experience around Silverlight/WPF that won't be there for this next development platform. You'll go to Google on how to solve a problem and find nothing but crappy MSDN documentation. IMO, the windev guys just arrogantly sit there an say "Hey it will eventually get there. People just need time to get over the change." Well for anyone from windev that happens to read this post a big shout out to you by the letters F and U.