If virtualisation (of hardware) is the way forward, then a virtual hardware standard needs to emerge. If that were then supported at bios level (or some intermediate low-level) the need for different device drivers would effectively vanish. This would make operating system development very much easier.
I have not heard of any effort to create a virtual hardware standard, and since Microsoft don't seem to be talking about it either, I suspect a significant move in this direction is some way off yet, certainly five years and probably ten.
Assuming there are no more debacles like Vista, I think Windows will survive for the foreseeable future. It is interesting to note that Midori is supposed to be lightweight whilst MS have stated that Windows 7 will be based on Vista not XP. No one could ever accuse Microsoft of being consistent!