oh you mean like linux?
no, not gonna happen.
Part of the reason I think iPads exploded is that they can do (with a few accessories) what 80% or so of the home computer market demands of their devices. For a large segment of society an iPad could browse the web, play a few games, and crank out documents which is why they bought a computer in the first place. Even before the iPad I knew a few people who paid for an iPhone instead of having a computer as the iPhone did what they basically needed from a computer.
As these tablets and smartphones get more advanced, more and more of the home computer market can be captured by them.
The average person doesn't really like computers, they like the uses of a computer (primarily the internet). Tablets aren't a fad, they are the future. The mouse is dying to touch in the next ten years.
MS's best chance is if it can find a way in Windows 8 to easily make it so apps can be mouse driven and touch driven. Then its a tossup.