Earlier quoted context omitted.
M2 seems very unlikely to me because that will create product misinformation easily. Imagine the following M1 -- 4 A14 cores M2 -- 8 A14 cores M3 -- 4 A15 cores That "third generation" sounds better, but is actually inferior to the second generation. X1 or M1x seem much more likely. It's the same reason why they made an A12x instead of calling it A13. They probably need 3 designs, but economies of scale begin to be a…
I always assumed the "M" in the M1 designation meant "mobile" and that higher-powered (in terms of processing, electricity, and heat dissipation) would be coming later and have a different letter designator. Either that or we'll get Air/Pro suffixes to the chip numbers (eg: M1 Pro, M2 Air...)
Though the fact that they've just labeled the chip in the latest iPad Pro as such does add a bit of confusion to that.