but I still feel like this transition is basically just another step for Apple and everything tech that wouldn't change much
This is going to be a game changer for performance, especially in mobile where processing power per watt is paramount.
Think: fan-less MacBook Air with the power of a MacBook Pro 15" and genuine all day (or even multi-day) battery life. Think: AR headset with light weight, great performance, etc.
This is pretty much almost possible today if they were to put an A12Z into a notebook. Future A series processors built specifically for larger form factors than the phone/iPad will be significantly more powerful - more modern technology, newer manufacturing process and physically larger processors will give much more performance.
The PC industry as a whole has been held back significantly by intel's processor stagnation since 2011 and AMD's failure between 2010 and 2016-2018 to have any competitive parts in the notebook form factor.
The iPad wasn't such a screaming success because Apple did such an amazing job. Apple basically successfully made what AMD and intel failed to advance to in their respective processor lines.
Both AMD and intel may recover and catch up, but Apple are done waiting for that.