They would have switched anyway.

Apple is all about controlling all parts of their phone and software.

Now they have a well working ARM chip they have all the control over which is good enough for at least the non developer models of their laptops so it was just a question of time until they switch.

I mean why _long term_ maintain two OS'ses and two CPU archs when you can just focus one one. (And yes I'm convinced Apple will turn macOS into iOS+some desktop features in the long run).