How much will the average user notice the difference between 4 and 23 high-performance cores? This will have a huge impact for highly parallel tasks like rendering, but isn't it still the case that most software still isn't designed to scale horizontally in a meaningful way?
I think the M1 is so impressive because the normal user will mostly notice the single thread and the low thread count performance, so the 4+4 configuration of the M1 hits that sweet spot. The most obvious gain would be from all the multicore loads. But for more and more heavy computing tasks, those get more common too. And I would expect any variation of the M which is tweaked towards performance rather than low power as the M1 is, to also offer a little higher clock speeds. Considering the M1 runs at 3 GHz and the most recent x86 at up to 5, there should be quite some clockspeed headroom, if Apple chooses to use it.
