I think it's important to remember that Apple has specifically stated you won't be able to run OS X on non-apple hardware. You won't be able to buy a Dell with Windows, decide you like OS X better, and then just install it over Windows. You'll need new hardware. Apple would go under if they were merely a software company; they are addicted to hardware sales.

Of course, nobody has any idea HOW they are going to prohibit OS X from running on Dells. Two guesses:

A. Draconian DRM chips a la XBOX.

B. Half-hearted 'official policy' and perhaps some weak protection that can easily be overcome by voiding your warranty.

The idea is that they will have to choose a technological solution or a social solution. The technological solution will be cracked eventually (see iTunes DRM and the heroic efforts of DVD-Jon). The social solution ("Running OS X on non-apple hardware will void your warranty etc.") will be ignored by the power users, but companies will follow it.

I'm hoping for B. Apple is often sympathetic to power users, even if they don't officially do anything to help them.