The M2 seems to be intended as a direct replacement for the M1 (and, as someone else has already pointed out, could quite conceivably be a pin-compatible,"drop-in" replacement) so once M2 production is cracked, Apple would probably want to end (regular) M1 production ASAP to free up capacity for M2.
It's not like Intel where there's a huge OEM market and the last couple of generations of chips would remain available to order for years - if Apple no longer needs M1s, nobody else will be buying them.
Dump M1 ASAP. Lots of that hinges on "possible". Apple probably isn't going to carry the M1 past 2022, but they probably are not in some 'desperate' hurry to do so.
You are presuming that the M1 and M2 are on the same TSMC process. That isn't necessarily true. If M2 is on TSMC N4 then dumping M1 doesn't free up anything because it is off on N5. If M2 is on the same process as A16 then Apple definitely would have a super high volume SoC to soak up N4 wafers. The catch is that probably can only so a limited amount of M2's for a couple of months before would have have to shift the bulk of the allocation to A16.
If Apple asked for N4 in late 21 and very early '22 because they though they could transition most of the lower part of the Mac and also the iPad Pro line up to M2 then there would be lots of capacity sitting there with few miniLED systems ready to go. However, there is a limited window here to produce M2 in high volume before the higher priority A16 would override that and M2 production would be limited until after the initial Fall iPhone demand bubble.
Since the Mac Pro and iMac Pro seem to be sliding into the second half of 2022, then just taking the MBP 13" M1 off the consumption list should be enough to give them some wiggle room on N5 wafers (e.g., more M1 Pro/Max for Mini Pro. No display so should run into fewer display parts shortages. ) . However, when Apple starts to wind down the A14-A15 off the N5 wafers that will be lots more room for. M1-generation dies. Hence, iMac Pro (with M1 Pro/Max) after that wind down starts.
September for iPad Pro ( so could start consuming M2's in July/August ). The MBA and "small" Mac Mini in October pulls the rest of the M1's from production and could soak some of that up with a M1 Max multi-die Mac Pro .
So anything with M1 that isn't being dropped or replaced will likely get bumped to M2 pretty pronto. If we just see an M2 13" MBP, and not M2 Minis, 24" iMacs and Airs (maybe not at the next event, but soon) then it would be a bit weird.
Not all that strange if they are constrained on M2 production because the iPhone had higher priority for wafers. That is where Apple makes most of their money. In May-August window Macs SoC competing with new Fall iPhone SoCs for wafers will probably loose.
So why introduce a ton of M2 products if don't have enough M2's to go around? [ the 'old' plan from 2019 could have been launch a bunch of M2 stuff in February and that initial demand bubble would be over by the time the "big ramp" started on the iPhone's SoC. The pandemic, miniLED growing pains, and parts shortages probably would have thrown that plan in the toilet. ]
If the M2 was meant to be a 'pipe cleaner' for the A16 then it is still a role that Apple probably would have stuck too. Just not as big of a production run before the A16 hit big production run.
