I think gwern's point (whose opinion on deep learning I respect a lot more than his on genetics) is that GPT-3 is nearly not the end of the story. OpenAI released a GPT pretty much every year and each one is a spectacular improvement on the previous one with no sign of that trend ever stopping. If size is really what matters at all, there's no telling what GPT-4 or GPT-5 might be capable of, let alone a giant GPT run by state-sized actors.