It's inevitable, Apple will move away from ARM based chips to..
As for power effeciency, Intel has already closed the gap and will far surpass ARM based suppliers with its trigate technology. It's absolutely amazing and unbeatable. ------
Except that no one believes Intel's 'roadmap'. Do you really think that MS would be going down the ARM road with Windows 8 if there was an x86 based ARM beater just round the corner?
Even if the power claims are true there are still two major issues that Intel needs to address (in competing with ARM). It needs an 'open' SoC approach so that end customers can add their own IP (Apple) and it must be competitive on price. Is Intel willing to sell a x86 SoC to apple for $20?