Earlier quoted context omitted.
Perhaps a combined SoC with both ARM and x86-64 cores, with independent switching like Apple already has for GPU integrated/discrete graphics switching. I think this would be a convenient middle way through this compatibility challenge. https://support.apple.com/en-us/HT202043
That would increase the cost, to include both x86 and ARM processors.
Now we know there will be a dev kit, new macOS, and that the new Macs will natively run iOS and iPadOS apps. Rosetta 2 will handle compatibility.
https://news.ycombinator.com/item?id=23604060
https://news.ycombinator.com/item?id=23603852