I think Windows 8 will do well and that will be a surprise. I think particularly with the less experienced PC user crowd. WinTel aint' done yet and there is still a lot of room for them to get together on phones.
The real pull is a consistent OS across all devices. Soon Intel will allow a smartphone to do what desktops only could do in the past. At that point the same OS and the same capabilities on each and every device someone owns is pretty convenient.
Microsoft can have a consistent OS and development environment without forcing the same user interface on all devices. Touch may work well with tablets, convertibles and smartphones but if one has large high res monitors their arms won't be long enough to reach to the edges of the display to use metro. And there are plenty of environments when one just doesn't want fingerprints all over their screen. In the future wearable computers may need to use voice control but it shouldn't be forced on every device that preceeded it.
That being said, Windows 8 has potential, especially if Microsoft stops assuming they know what works best for PC users than the PC users themselves.
And yes, it is likely that smartphones will carry the power of today's ultrabooks.