> but the Neo may be proof that decades old macs could run Tahoe, and maybe as well or better than the Neo

The A18 Pro is going to out perform many "decades old" processors, which would you be referring to?

I wouldn't conflate "affordable" with "low-end" in terms of processing speed. Apple is able to get the price to this point because of decisions that the rest of the market did not make.

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.