The main thing Apple has done to improve their A-series chips has been massive L2 caches.

I still major advantages of putting a A-series chip into a MacBook Pro.

1) There will be a much larger thermal and power draw envelope available to new A-series chip. I suspect we will see insane “boosting” clock speeds.

2) Incredible “at idle” performance well beyond what X86 can provide with on did GPU cores, which means a bit better battery life for that screen.

3) More opportunity for tightly integrated acceleration chips On die for codec, ML, and other hardware acceleration methods for Apple only software libraries.

4) Easy porting between iOS and macOS, and tvOS.

#3 will be the most significant.