I expect Linux to sneak onto the desktop in the form of Android. The Motorola Atrix, an upscale Android phone, already comes with an optional netbook attachment - you can dock the phone into the back of it and it lets you interface with the phone with a netbook's keyboard, mousepad and screen. It's not rumored to be an especially good netbook, but the time will come, probably within a few years, when something like it will be.

There will be no reason for most people to maintain a separate computer when their phone is powerful enough to do everything they need, except that its form factor is inappropriate. It will be cheaper and simpler just to dock it in a shell that gives a more appropriate form factor.

tldr; Android will disrupt the laptop/desktop market.