Might rather see it the other way around - Nvidia getting license to create products with x86(_64) CPUs integrated in the silicon. Nvidia are the big boy in this transaction and they'll get what they want out of it. But I can see the attraction for Intel.

I don't think they can, as AFAIK the agreement for x86_64 is that Intel and AMD cannot change hands. AMD will surely fight this tooth and nail in the courts

But with the state of the courts today... who knows..