The long arc of history is towards performance per watt.
Apple knew that when it invested in Arm and chose Arm for Newton, for the iPod and the iPhone (note Apple has been selling Arm based products continuously since 1993 apart from 1998-2001).
It’s no accident that there is an Arm based CPU in the Mac now. Apple’s most important Mac is the MacBook and performance per watt is key. Until someone can offer an architecture that demonstrably does much better on this metric Apple will stick with Arm.
The performance per watt point is a more than fair argument. It also cuts both ways. If Apple decides ARM is still the performance per watt leader in 20 years, there's a good chance they'll still be using it. If any other processor tech reaches a better spot, they have the expertise and the semi-closed ecosystem to switch processors quicker than pretty much anyone else in most of the spaces into which they sell. It's something they've not only done multiple times, but done well and are known for doing well.
100%. Look what happened with GPUs and Imagination. Personally I think CPUs and ISA will become less important as more functions are passed to special purpose engines. Perhaps RISC-V extensions might be a trigger but I suspect Arm will offer Apple whatever they want to keep them (both on the ability to add new extensions and on price - if they are paying anything at all at the moment!)
Apple knew that when it invested in Arm and chose Arm for Newton, for the iPod and the iPhone (note Apple has been selling Arm based products continuously since 1993 apart from 1998-2001).
It’s no accident that there is an Arm based CPU in the Mac now. Apple’s most important Mac is the MacBook and performance per watt is key. Until someone can offer an architecture that demonstrably does much better on this metric Apple will stick with Arm.