This is not as easy as it sounds. AMD will loose it's x86 license if acquired without Intel permission. Designing an efficient parser for a different instruction set can take years.
I'm pretty sure that the patent situation between AMD and Intel is one of mutually assured destruction, given that AMD created the 64-bit extensions to x86. Intel could complain a lot and file some lawsuits, but if they seriously tried to block the acquisition of AMD, they would be putting their whole patent portfolio at risk and opening themselves up to billions of dollars of punitive fines from antitrust regulators.
Not really: "However, the agreement[43] provides that if one party breaches the agreement it loses all rights to the other party's technology while the other party receives perpetual rights to all licensed technology."
That sentence doesn't seem to be supported by the citation as redacted and posted online, or I just can't find the relevant language. It looks to me like the list of sections that survive the termination of the agreement doesn't include section 3, which is the actual cross-licensing section. I'm not a lawyer, though, so please point me to the section that has that effect.
Even if the agreement does stipulate that AMD's patent license to Intel becomes perpetual upon termination due to change of control, I really doubt that it is legal in the US, since it basically means that a third party can't buy their way in to the market unless they bribe both AMD and Intel to weaken the duopoly. That would seem to amount to a cartel.