That's the thing, Apple fans will just keep buying Apple no matter what. Even if you could by a PC with OS X there would always be a demand for Apple hardware. If Apple sold OS X separately from Macs people would still buy Macs.
I'm a long time Linux desktop user, since the days of Debian Slink and Windowmaker, but I dig OS X. It's slick. I wish there was a desktop on Linux that could strike that balance between features, usability and stability. That being said, I'm also cheap. If Mac's were more competitively priced, I would probably own one, but paying that much over market value for what essentially is a "pretty" PC that can run OS X has always been an issue for me. I just chug along on my aging but sturdy Thinkpad with Linux. I think Apple could change the game if they decoupled OS X from the hardware. Who would pay for Window 8 when you could just install OS X instead?