N3B: M3
N3E: M3 pro, max, scalable
IMHO, why N3B as first 3nm process it's the most risky/low yield, indeed I won't expect it on high volume high transistor count SOC. That's for n3b, the God news is apple may not Skip m3 for 2nd gen ASi Mac Pro.
This is exactly backwards if N3B is 'very , very bad' for high volume. The plain Mn die is an over 10M/year run rate die. ( The MBA , MBP 13" , iMac 24" are over 50% of Mac sales . At about 20M/yr that 10M right there. Still haven't included the iPad Pro and iPad Air. ).
Pretty good chance that all the 'drama' about N3B having really bad yields is pretty overblown at this point. N3B extremely likely costs substantially more (perhaps 'bad' in an environment where most vendors are looking to cut unit costs to protect margins) , but Apple is pretty brave at throwing additional component costs at user pocketbooks rather than their own.
N3B : scalable ( 2 or more )
N3E : M3 , M3 Pro , laptop only Max
might be true. If Apple started
all of them on N3B design and then later did a substantive redesign for N3E , then the scalable one was already in the expense zone. Throwing even more design overhead costs at it only would make it even more expensive. The price is already high and the run rates relatively low so is far , far better position to absorb incrementally lower yields. (Apple's mark up is large total amount on these high end chips per unit). The 'scalable' model is not a high volume SoC. It is much bigger , but not high volume. ( yields are already incrementally lower just being bigger). If the denser cache memory of N3B was the dominant source of the yield problem that would push all of them over to N3E. There would be a problem if the disproportionately higher cache memory presence was a root cause problem issue. But that isn't a 'high volume' issue. N3B yields are probably incrementally lower than N3E yields but Apple is charging 100's of dollars more for the 'scalable' chips also. The discarded dies are being paid for.
Going through a substantive redesign for N3E would incur a substantively delay. M2 just came out in 2022. It isn't even a year old. Sliding into late 2023 / early 2024 isn't any worse than the M1 -> M2 time gap. M2 Pro/Max are even younger!!! Apple needs new ones of those 'soon' like they need another hole in the head. ( The Pro isn't a "hand me down" SoC. Once replaced in a MBP 14/16" or Mini Pro it is gone from the product line up. Max is relatively "fall off a cliff" worse. )
That said. I'd be surprised if Apple 'split up' the M-series across two different design nodes. If N3B was so 'bad' financially it chased away A17/M3 then pretty good chance the rest will follow suit. And the 'scalable' would take a price and time hit ( e.g., the very low top end variant disappear because now 'too expensive' by saddled with a 'designed twice' cost. ) . Apple would take negative hit on Mac Pro 'timely arrival' though.
All on N3B in 2023 and wait for N3P for some limited line updates next year also would be tractable (presuming the doom and gloom about yield are overblown. ) N3B takes longer to fab, but Apple can work around timing with a good plan and temporarily willing to carry some incrementally higher SoC inventory than usual periodically.
The only Apple SoC that has a better chance of being completely split off is the A17. There are lots of 'hand me down' products for that so the economies of scale are just way better than even the M3 (let alone the rest of the M3 era line up). But timing wise it would be rather risk if Apple wants the iPhone Pro models to come out on time. N3E probably won't be in HVM production with enough lead time to hit a demand bubble at the end of September.
N3B probably will be a worse fab process for any 'long term' product that is going to be used in multiple generations of Apple products. If Apple wants to play 'hand me down' if the A17 into a plain iPad in a couple of years then probably worth taking a short term rollout out hit, to have a SoC that can make for several years.