I don't have any more information than anyone else, but I think people are confusing the desktop UI with Win32 applications. They are 2 different things. The desktop UI is just the old flat screen with icons and the start menu. That was replaced by the Metro tile based UI. You can however still run Win32 apps from the tiles.
While the start menu and Windows desktop UI will likely go away completely soon, there there is no way in hell that desktop *applications* themselves (applications based on the Win32 SDK) will not be supported in Windows anytime soon. It would be business suicide for MS to do that. I suspect it will be 10 years or more before Win32 applications stop being supported. Its possible that 32 bit applications might be phased out quicker but 64 bit apps, unlikely. Anyone remember how long it took to phase out 16 bit DOS applications?
As much as Microsoft would like to get rid of Win32 (to reduce their support and maintenance costs obviously) its going to be a long ride. There are millions of applications built on Win32 and they won't go away overnight. What is likely to happen IMO is that the new WinRT framework will get richer over time to a point where it won't have some of the limitations that it has today. At that point most app vendors would have migrated their apps to WinRT. Even if desktop UI itself goes away completely in future Windows OS's, there will most certainly have to be a way to launch Win32 apps - you can do that today from the metro tile UI. And even if MS removes that there will be 1 million 3'rd party desktop replacement's that will allow you to do this so I wouldn't worry too much.
While I personally don't think WinRT is a mature enough replacement for Win32 yet, at least for the needs of applications like ours, Win8 was definitely a step in the right direction for Microsoft. Just look at what you can do with touch and the ability to move seamlessly from a desktop PC to a tablet/mobile pc running the identical app, which is killer! I suspect some of the clunkiness with the initial Win8 transition will be improved in the next generation OS. Most of it is just the user interface dealing with the new UI paradigm and not the OS core itself.