I agree with all you say. I just wonder where this sits in the matrix. Is it a macbook / MBA ? I never thought really a high end MBP would come out first, but also not a 12”. A 13 / 14” macbook would definitely be a hit and I will be first in line for this, as it is exactly what I need and dont intend on using any Rosetta2 apps [if possible].My bet is on an entry-level Mac laptop. Whether they call it MacBook, MacBook Air or whatever is a secondary question.
Why do I think so: it would make sense for Apple to start with “simpler”, more conservative A14 variants. An A14X with 4 high performance CPU cores and 7-8 GPU cores would have good yields, could be reused across iPads and Macs, and it wouldn’t need any novel approach to main board design. But it’s also not really a CPU you want to use in a higher-end 13” MBP, because as @calstanford mentions, a lot of initial software will need to run under Rosetta2. For an entry-level, cheaper Mac laptop though it’s going to be amazing. A 1200$ Apple ultraportable with excellent battery life and performance rivaling more expensive Tiger Lake laptops is going to be an absolute hit.
It certainly is going to be interesting to see how this all works out over the next year or so, regarding apps.