I was under the impression that it wasn't windows 8 as much as the graphical fidelity curve being topped out. We're almost at photorealism with the current high end hardware now, and with my 2 year old medium-budget rig i can still run nearly all new releases on "high" graphical settings without any problems, so why would I want to upgrade?
I do agree that Windows 8 makes be recoil and hiss like an angry cat whenever I see it, though. I think microsoft have to realize that the new era of Tablets and mobile devices has split the old PC customer base. People simply want different things from a tablet than they do a PC, same with a mobil platform like a smartphone. Sure, some will migrate to the platform they feel suit their needs the best, but there are still things that PC's can do and Tablets can't, and vice versa.
Not to mention the crucial familiarity factor. People are familiar with the old windows interface and look for something similar whenever they actually upgrade. We're creatures of habit, after all.
It needs to be mentioned, though, that we're at the end of a console generation and the enthusiast crowd is waiting to see what's going to happen. People are holding onto their money in anticipation of the new console lineup, and when all the options are presented, only then will we begin to see which way the new trend will head. Maybe PC's will be relegated to business and enthusiast crowds only, or maybe the consoles will fade and PC's will experience a boost?
I personally don't like consoles, so am hoping for the latter, but it could go either way. We'll just have to wait and see, because right now the whole market is holding its breath.