well... lots more... PC's in the world... that would sell LOTS of OSX's... "pretty much total profit and at $120 or so a pop" ... now, those customers, MAY purchase a mac on their next machine or just get a PC with OSX again... but, you are still getting $ from them... where before you were getting nothing...
You do know that the development cost of OS X is much more than $120 per copy, right?
Apple would have to sell every copy of OS X for PC at a loss.
So you are proposing that Apple should make a loss on every sale, but make it up with volume?