You are right that developers are only a small part by volume. However they are the most important users in an environment, as they the ones creating new applications. Same with other power users, who require a VM. Driving them away from the platform could have a much larger net effect. That Macs got much more popular after the switch to x86 hints at that the compatibility isn't quite unimportant.

So I do think that Apple is probably going to ARM, but they need to be very careful in the steps they are taking and they need to have a really compelling offer so that users are willing to go through the transition.