Are you referring to Apple's laptop x86 -> ARM change? Entertaining the idea that the ISA is significant here: Surely there would be a big market for ARM chips

Are you referring to Apple's laptop x86 -> ARM change? Entertaining the idea that the ISA is significant here: Surely there would be a big market for ARM chips in the Android and server sides too, so this shouldn't be the only reason why other vendors aren't making competitive ARM chips. Apple's laptop volumes aren't that big compared to those markets. And of course you have to factor in the large amount of pain that Apple is imposing on its user and ISV base in addition to the inhouse cost of switching out the OS and supporting two architectures for a long time in parallel. A vendor making chips for Android or servers wouldn't have to bear that.