I'm not sure this really makes sense. The single core performance for the iphone chip is leagues ahead of anything even a couple years old. They can likely increase clock speed of the iphone chip in a larger chassis so the performance isn't exactly 1:1 with the 16 pro, which was hardly a slacker. 8gb on apple silicon goes much further than 8gb would have on an intel chip, due to faster and on chip RAM and much faster storage to enable smoother use of swap.
I'd agree that an m1 chip can probably continue to run modern macOS for a very long time, and they will likely drop support for it much earlier than they would need to.
I'd agree that an m1 chip can probably continue to run modern macOS for a very long time, and they will likely drop support for it much earlier than they would need to.