Cores is an interesting question.
Fun fact: In the 1960s when mainframe went from 1-core to 2-core we got 1.1X.
Now, 50 years later we scale nicely to 190.
This is not my attempt to praise the mainframe but rather to impart what I’ve learnt from a very long timeline with hardware and software developers who are about as clever and determined as those in Apple.
The interesting thing is how you design huge multiprocessors - to minimise what we call the “MP effect” - namely how that 190th processor yields as close to as much as the first.
Inevitably, beyond a certain point you do it by ganging together multiple chips, each with many cores. (190, for example, is a 12-core PU chip with 20 of these chips working together via a sophisticated cache hierarchy, System Control chips, and communication protocol. Yes, lots of these 240 either aren’t used or are used as eg I/O processors.)
Now back to Apple Silicon: I would hope the architecture has been designed in a similar way.
I could conceive of eg Mac Pro, iMac and Mac Mini being re-architected in a similar way to get us to eg 64 or 128 cores - with good MP ratios. There is the physical space.
I could conceive of a (16”?) MacBook Pro with 2 PU chips, getting us to 32 cores - again with good MP ratios. Again, there probably is space and appetite for it.
I could imagine M2 being 16-core, or maybe just 12-core.
All of the above necessitate M2 supporting more than 16GB of memory and more I/O capability (bandwidth and ports).
What will get to be interesting is whether MacOS can drive this efficiently and effectively. (Our operating system, z/OS, has had to do much work over the decades to enable the hardware to achieve excellent MP ratios.)
(Just a few thoughts from a highly experienced / old Performance person.)