No idea from a legal perspective.
But from a pragmatic perspective, after the near meltdown of Apple back in the ‘90’s when they attempted licensing out the Mac OS to third-party platform vendors, I hope it never happens.
The Mac is experience is intended to be superior, even premium. And Apple is able to do that, in part, by having complete control over the hosting hardware.
Compare just about any official Mac product to a comparable PC from Dell, HP, whatever, and you’ll see that price out nigh identical, often with the Apple even slightly cheaper.
That said, I think Apple is missing out on a key market segment:
I don’t want or need a machine with a built-in monitor, I don’t need the power of an eight-core Mac Pro, but I’d like my Mac to be faster and more expandable than a Mini. […] Tired of waiting and hoping for the Mac of my dreams to appear, I decided to take the technology into my own hands and build it myself. And thus began my experiment to assemble my very own OS X-running machine.