3nm was known when TSMC published the technical details, and TSMC somewhat pushed finfets as much as they could, with the SRAM not scaling being a drawback. But they went for maturity over rushing new transistor tech before they thought it was fully ready for mass production (we can see how that worked out for Samsung). But it was never expected not to scale any further, just that going forward it would scale much less vs logic.
Either ways though, whether it scales or not, the higher cost of the new nodes will itself make using more SRAM challenging for all but the highest margin chips. So having tech like AMD's will be an advantage.
