ARM, for low power and performance efficiency, is better, and that is why. It gets more ILP, and ILP is more efficient than TLP (which is more efficient than PLP, but yeah).

AMD64 is entrenched. It's what Windows works on. It's what the entire PC ecosystem works on. The PlayStation and Xbox runs on AMD64. Whether we like it or not, it is here to stay.

I deliberately didn't discuss any switch to ARM, as it's almost certainly not going to happen and I was responding to someone who was saying that making more efficient CPUs was a better idea than better fans.

It is, of course, but it isn't going to happen to the level ARM allows it to.