Since usually the M series chips are based on the a series chips does this mean that M3 will still be on 5nm? M2 was based on a15 if I am correct. And if M3 will be based on a16 then it will be a 5nm chip too. So we may have to wait for M4 chip to be on a smaller process node some time in 2024?
There are two presumptions here that don't have to hold at all.
1. Apple "has to" roll out new cores from smallest SoC to bigger SoC.
There is an equally viable path where they roll it it from bigger SoC to smaller one.
For example
M2 Extreme (Quad) on N3 Jan-Feb '23 ( smaller M2 arch that is easier to package)
M2 Ultra on N3 March '23
M2 Max on N3 April '23
[ Skip putting the M2 Pro on N3 and keep it on N5p high volume , low risk ramp ]
A17 on N3 Sept '23 (pilfer the shrunk P and E cores from above , slap some new uncore element ( better ProRes , camera ISP , etc. and call it A17. That is a bit more 'honest' than yet another serving of the same thing. )
Apple would only be putting the Mac Pro at risk eariy in the N3 cycle and those system pricing will be average well over $6K so the SoC have a high market up attached.
Using a high profit margin , low volume die works about as well to 'pipe clean' as new fab process as ' low margin , very high volume ' die. Either use a chunk of the large margins to pay for the higher than desired defect rate. Or 'duck'/avoid the defects by being a smaller chip and lots more dies coming out of a wafer so can afford to amortize in smaller chunks those defective dies.
50 dies per wafer that generate $1000 profit per die generates as much money as
525 dies per wafer that generate $96 profit per die.
Also rolling out the Mac Pro on N5P up against N5P AMD and N4 Nvidia GPUs is just asking for trouble. The iPhone SoC have a larger lead over the competition. At the high end of the worktation market ... M-series doesn't.
2. The M3 does not have to be based on the A16 at all. There is presumption there that the M3 has to come out in 2023. (e.g,, Apple has to put the MBA on some yearly cadence of updates just like the iPhone). Apple doesn't have to do that at all. In fact, they did not do it for the M1 -> M2 transition and things worked out just fine.
A17 on N3 Sept '23
M3 on N3 Feb '24 . ( about ~18 months after M2 )
The A14 and M1 showed up around the same time.
If the A16 a yet another N5P retread with just about the same microarchitecture then, that is indicative that Apple spent most of their time and money doing something else. Perhaps that is a new AR/VR SoC ( on N3 ?) or some other part of the line up to N3 sooner rather ( Spring '23 ) than later ( Fall '23). Or the cellular modem is a black hole of resources and a distraction.
TSMC N3 comes with some new Technology (FinFlex) which should have a higher learning curve on it. So taking an architecture they have worked the bugs out of and then mainly concentrate on making it small would be a good way to manage risk.