They should focus on high-quality expert answers.

Now that we have LLMs I don't need basic questions answered. I do still need hard questions answered by experts and AI has normalized paying money for QA.

I would definitely pay for a "human ChatGPT" service where the answers are written by experts who get paid per answer, e.g. grad students. Then they can resell this data to AI companies. Or maybe the economics are such that they can take enough money from AI companies to pay the experts and I don't need to pay anything at all.

This won't bring in as much money as advertising used to, but that business model is dead anyway. There's no future for a QA site at the low end.