I don't think that's quite a given. I don't think Apple has changed as much as you're implying. When OSX was first released, even though it was Unix-based, most people were pretty confident it wouldn't ship with a Terminal. Apple has always been very opinionated and strongly biased towards a user-facing experience. "Techies" have always been a bit skeptical of what Apple may do and should continue to be.

Linux already has a very healthy ecosystem on ARM with Raspberry Pi and others. Heck, it had a healthy ecosystem back in the day on PPC with thins like Yellowdog Linux. I don't think an ARM transition will change this part as much as people think. You've always needed to recompile for macOS.