If you think Intel would eat its own shoes before it adopted AMD64, guess again, it will be compatible with AMD64. If you doubt this, think about one thing, why this is happening. It is not Intel's doing, not by a long shot. While it may use a different name, like the old x86-64, or even Extended x86, it will run all the software that AMD does. Mmmmm, shoes are tasty.
So, why is this again? Simple, MS. Microsoft will not support a different 64 bit platform, and frankly I don't blame it, it costs a lot of money to do that. MS gave Intel the choice, support AMD's instruction set, or do without Windows. MS won that battle pretty handily.