Why would anyone leave Apple over the ARM move? Apple have said that 1) they still have Intel-based Macs yet to be announced, and 2) they will support macOS on Intel for many years.
So yeah, we could have this discussion in 5-6 years. But to have the discussion today is stupid.
The following people shall leave for sure:
1. Those who also need to run Boot Camp for their CAD software. CAD on Mac is horribad.
2. Those who want Boot Camp for gaming.
3. Those who need x86 compatibility because... God forbids, there are, oh... ZERO cloud server that's actually running ARM.
4. Those who want a Mac they can upgrade 5-6 years down the line by putting in more RAM, a new GPU, etc...
5. Those who want to develop their software for other platforms that are not Mac.
6. Those who are not willing to pay the "Apple tax" when Apple releases that next MacBook that costs the same or more than the current lineup, but with a chip that they make in house and don't pay for royalties or anything of the sort.
These 3 factors will make me leave for sure:
1. The next MacBook is more expensive.
2. The next MacBook has less GPU performance because... I don't know, it's super easy to scale from a phone GPU to a desktop-class GPU, right?
3. Apple does not address the bugs that are currently in Catalina that are plaguing my 16".
Apple is moving too fast. I am actually HIGHLY disappointed they are introducing Big Sur with all new sparkly features and completely ABANDON us 16" MacBook users who still need a software fix for our graphics cards when connected to multiple monitors. They have proven to me at this point that the ARM move does not benefit me, and will only benefit them. So why do I have to continue supporting them again? Steve Jobs at least could tell me why I needed to support him. Tim Cooks is failing very badly at doing exactly that.