Performance? That was the whole point of ARM
"* Performance, ARM processors are designed with power efficiency in mind. Look, I'm a Brit so "rah rah ARM". But they are not designed for performance and will be absolutely hammered by Intel/AMD in this regard for laptop processors."
Have you ever run comparable machines side by side? Even at the beginning with the Archimedes, ARM chips kicked the normal desktoip class processors clock for clock, as an example in 1988 if you took a Mac, an Atari ST and an Amiga and put them up against the Archimedes A305 (The bottom of the range machine), all running at around 8MHz, the Archimedes left the other machines for dead due to the processor architecture.
There are numerous reasons why the Archimedes didn't take over the world, including price, lack of compatability with current and emerging standards at the time, and Acorn's relative obscurity outside of education, especially in the UK, but performance was not an issue.
As for cost of a FAB, there are more ARM chips manufactured every day than any other processor, and there is no reason why an Apple chip cannot be manufactured alongside someone elses chip as the core processor is the same. ARM Technologies own the processor, but other people make and distribute it for them.
Ok, the point on emulation is pretty valid, though did PPC emulation really hit pattery power on a MacBook or MacBook pro? I didn't notice much if any difference, if anything XP under boot camp hit performance the most (And even then not by as much as many people claimed at the time).
IT would be good to compare a 2.4GHz 64 bit ARM chip with a 2.4GHz 64 bit intel chip, but as only one of those exists for the moment, we can only speculate on the outcome.