Win8 Too little, too soon
At least for the desktop. Win7 is still running in many places and for those, (lagging) places, a new UI is not a feature, its a bug.
For those which have done the migration, doing another one probably isn't on the cards.
Where Win8 will go ahead is on consumer OEM PCs (no options given) and probably in servers where moving the GUI out of the kernel is a plus. However, companies which like that are probably either *nix already and just moving windows platforms - no hurry or much profit there.
The other place is the laptop-cum-tablet combination for home use. Requirements are simple and you save buying an extra (expensive) screen & battery. I suspect MS will put "co-marketing" funds into this to prevent the same hardware designs appearing with android.
Mostly business use involves clicking a a few desktop icons, one for each app. Employees are generally discouraged from using OS features.
The problem with the PC market is not the OS, its the lack of hardware innovation. Why does the best PC thing in recent years (thunderbolt/lightpeak) have to come from the most closed company? We want more connectvity and more availabilty. Faster CPUs and higher core counts only go so far. I've noticed recently that dual-gig ethernet seems to be disappearing from desktop boards. Bzzt, there goes AoE, decent iscsi at home etc.
Personally I'm mad at intel. I've got a socket 775 mobo. Since then, we've had 1366, 1156, 1155 and 2011, but a top end 775 CPU (Quad-9650) is about the same as a good i5, upper-middle i7 and costs the same (if you can get it). So much change, so little benefit. You might think it was all for the benefit of the chipset makers to prevent pure CPU upgrades.
Win8 won't save the pc market. The PC market just got boring. Look at all the identical PCs - that's the problem, no innovation. Has anyone seen a PC with an extra ultra-low-power core for when not much is going on? If anyone can find a high-power graphics card which can sleep while the PC is on, please let me know. I don't mean just put the screen to sleep, I mean turn off that loud fan on the GPU so I can sleep while downloads continue or while my wife streams video from it to her tablet.