There's another set of M1 based SOCs definitely planned, though details are all speculation. I like the idea circulating that M1 (and eventually M2, etc.) designate chips with the same 5nm process, using the same general architecture, but there will be variants, i.e., M1 + <some_designation>. You know, not unlike the A12, that had an A12X, an A12Z (as core counts increased).
So figuring on an M1<something> for the next flavor, that will find a home in a higher power 13" (or maybe a 14"), and the 16" MBPs. A nice bump in core counts, like 12-16 for CPU/GPU (I'd guess just retaining for the 4 low power CPU cores ...), 24 core ML subsystem, maybe a little fudge to the clock speeds, plus 32, maybe 64GB RAM options, and at least 4 TB/USB-4 ports (with the ability to drive 2-4 external displays).
Yeah, I'm thinking (hoping) we see something like a Mini Pro that gets the next M1 variant (and all the improvements I mentioned). The current M1 Mini has a ton of available space too, so more storage and/or better cooling, etc. , plenty of panel space so could easily get 6 ports - and pricewise, the 16GB/512GB M1 model is $1099, and gives my i7 a run for the money, and decimates it in terms of graphic (GPU) performance (the Intel machine being $1499, though I actually have a factory 32GB Mini ...)
If the RAM pricing was the same for the 16_to_32GB bump as Intel, that's +$400, no idea about the next gen M1, but even if it was another $400, a Mini Pro, 32GB, with say, 16 CPU cores, like 16-24 GPU cores, that could drive 4 displays at 5K, with graphic performance reaching high-er-ish end discrete GPUs? For under $2K? Take my money!