If Apple uses the A16:
M3 will either stay on 4nm or Apple will have to redesign the A16 for 3nm. The A16 was designed for 4nm because 3nm was delayed by TSMC. 3nm is a full node upgrade which means design rules are different from 4nm. Porting A16 to 3nm would be a huge effort. It might not make sense because the A17, a ground-up 3nm design, is coming out in Fall 2023.
If Apple uses the A17:
M3 will certainly be 3nm because A17 is extremely likely to be a 3nm design. This means Apple would skip the A16 altogether. It's possible that Apple had always planned to skip the A16. TSMC shares node roadmaps with Apple years in advance and Apple might have had the team develop the M3 and A17 side by side, like how the M1 and A14 were designed side by side and launched within 2 months of each other.
If Apple uses the A17 for M3, we might not get the M3 until Fall 2023 because that's when the iPhone 15 launches. It'd be weird for Apple to launch a SoC using A17 cores before the A17 because the iPhone is Apple's most important product by far. There's also a chance that M3 will come out in Summer 2023 if Apple developed the A17 and M3 side by side and is ok with Macs getting the latest SoCs first. There's already a report by Marc Gurman stating that the M2 will be a short-lived generation which means we could see the M3 sticking to a 1-year update cadence and launch during the Summer.
M3 will either stay on 4nm or Apple will have to redesign the A16 for 3nm. The A16 was designed for 4nm because 3nm was delayed by TSMC. 3nm is a full node upgrade which means design rules are different from 4nm. Porting A16 to 3nm would be a huge effort. It might not make sense because the A17, a ground-up 3nm design, is coming out in Fall 2023.
If Apple uses the A17:
M3 will certainly be 3nm because A17 is extremely likely to be a 3nm design. This means Apple would skip the A16 altogether. It's possible that Apple had always planned to skip the A16. TSMC shares node roadmaps with Apple years in advance and Apple might have had the team develop the M3 and A17 side by side, like how the M1 and A14 were designed side by side and launched within 2 months of each other.
If Apple uses the A17 for M3, we might not get the M3 until Fall 2023 because that's when the iPhone 15 launches. It'd be weird for Apple to launch a SoC using A17 cores before the A17 because the iPhone is Apple's most important product by far. There's also a chance that M3 will come out in Summer 2023 if Apple developed the A17 and M3 side by side and is ok with Macs getting the latest SoCs first. There's already a report by Marc Gurman stating that the M2 will be a short-lived generation which means we could see the M3 sticking to a 1-year update cadence and launch during the Summer.