Just because something is technically feasible doesn't mean that it's a good idea. A seekingalpha.com article gives 10 reason, none of which are very good, that Apple should buy AMD. Let me give you my top 4 list of reason Apple shouldn't and won't buy AMD.

1. Intel kisses Apple's ass
2. Intel gives Apple pretty sweet deals
3. Intel current has better technology than AMD
4. Apple didn't have to buy Intel to get the first three items

It might have been a good idea for Apple to buy AMD when they were switching from PowerPC, but now it's just silly.

Disclaimer: I work for Intel. These are just my opinions, I have no inside knowledge.