Comment by wmf
PS5 had Zen 2 which was fairly new at the time. If PS6 targets 120 fps they'll want a CPU that's double the performance of Zen 2 per thread. You could definitely achieve this with ARM but I'm not sure how new of an ARM core you would need.
Is there a need to ever target 120 fps? Only the best-of-best eyes will even notice a slight difference from 60.