My guess is the max will just have the better gpu option.
Long term though, there's no doubt that Apple will be aiming towards more cores for the iMac and Mac Pro. It would be pretty awesome if we saw an even crazier cpu option with more cores.
Most likely:
M1: 4 performance cores, 4 efficiency cores. Same for M2 later but faster.
M1 Pro: 8 performance cores, 2 efficiency cores
M1 Max: Same as pro but with more gpu cores
Would be awesome:
M1: 4 performance cores, 4 efficiency cores. Same for M2 later but faster.
M1 Pro: 8 performance cores, 2 efficiency cores
M1 Max: 12 performance cores, 4 efficiency cores or similar, probably would be re-used in iMacs later since they will have a larger thermal window. On a 14/16" though they might need to keep frequencies down on something like this.
Overall I'm a little worried that these higher powered Mx chips will lose the coolness of the M1 that makes it so appealing for laptops. They almost certainly will be adding 10-20w more power draw.
I'm posted it a million times before but I'm also impatiently waiting to see if Apple supports wi-fi 6e (6ghz) or AV1 hardware decoding in these chips.