@DeathByVisualStudio: I'm not sure I see your point.
Even if we got a new version of WPF instead of WinRT, I'm afraid that you would still have to develop and maintain two separate clients: with very few exceptions, "Metrofied" desktop apps are gigantic piles of failure. The converse would be even worse.
This sucks, of course, but it's nothing new: it happened every time the Windows UI underwent a major facelift. Sure, this time they also grafted a few extra limbs and changed the blood type, but this is kind of immaterial at this point.