Jay Machalani's concept for fixing the Metro+desktop are the way to go IMHO. http://jaymachalani.com/blog/2013/12/12/fixing-windows-8
Basically the concept is to include both the Metro + desktop UIs and let the user explicitly choose. When you're in tablet mode, all desktop apps run full-screen (or using the Metro-style split screen) and when you're in desktop mode, Metro apps run windowed like Desktop apps.