If Sam feels that people are overhyping the next version, it's probably because it's named "GPT-4", which implies the same (or better) jump from GPT-2 to GPT-3, which was massive. The naming suggests the improvement will be that much. Name it GPT-3+ instead to temper expectations.

This is assuming that he actually cares about it being overhyped though. He could be secretly enjoying and fueling the publicity. In that case, he better deliver, because disappointing your audience is hugely damaging.