In a world where latency:storage size tradeoffs need to be made for practical reasons (and will, at some point, be required for fundamental physical reasons), we should just embrace NUMA anyway. Death to the lie of uniform access! NUMA is the future!

Ehrm, anyway.

It actually isn't clear to me whether designing a two socket motherboard is fundamentally an easier task than jamming more of the things into a single package (given that they have already embraced some sort of chiplette paradigm).

I believe designing/manufacturing a 5nm chip only used for Mac Pro can't be profitable. That's why they designed M1 Ultra as MCM of M1 Max.