While no doubt hacks will be released to allow at least Windows on the Mac and perhaps OS X on non-Apple hardware, I would not expect hundreds of thousands, much less millions, of users to run out and do so anytime soon after the capability is announced.

If the hacks are even remotely "complicated" or "involved", you'll be looking at only the "hard-core" types doing this. I mean even dual-booting two versions of Windows took some effort in the early days.