In that timespan RISC-V could leapfrog ARM in overall performance (including power usage and price) -- who knows? Performance improvements have been a big driver of those previous migrations.
It was essentially the same with Intel and Arm, plus the fact that they could save money and further integrate vertically.
(As I recall, but maybe I misremember, Apple claimed a big performance advantage for their high-end G5 Macs but in the real world it was a bit dubious.)
They have an ARM architecture license. They design their own ARM implementations from the ground up.
If something can be done to RISC-V designs that would leapfrog ARM and ARM does not want to incorporate whatever breakthrough that is into their own cores for some reason that will mean that the people who rely on commodity ARM chips or on licensed ARM cores will be out of luck.
Apple on the other hand would be free to incorporate that into their ARM implementation.
RISC-v is an instruction set. If any company made a better RISC-v core than Apple can make themselves they could either buy it from them or make their own faster ARM core.
That’s what happened with Intel and PowerPC…
What improvements in the instruction set itself could make RISC-v fundamentally faster than equivalent ARM chips?