This is the elephant in the room that OpenAI and Anthropic specifically aren't talking about -- when "good enough" is surpassed.
Because there are a large number of use cases (and large sub-portions of others) where genius-level AI isn't required.
Which means once that threshold is surpassed in people's relevant fields, available margin on that is going to collapse to commodity levels.
It's difficult to see how either pure-play AI company maintains its valuation once that happens. Their TAM is based on capturing a big chunk of all work, not just that which requires the highest intelligence.