The other thing I'm wondering, even though this is veering quite far off the original topic, but: I don't just want all the sources that the AI used in responding to my question, I also want all the other sources that seemed relevant to my question but were for some reason not used.

I want completeness (i.e. if source material is being skipped, I want to be the one to make the decision that it can safely be skipped), and I want consistency (i.e. I want to be able to double-check that the same set of sources wouldn't also support drawing conclusions that contradict those drawn by the AI).

In other words: I'd still want to use search as a product, and I'd still want someone to solve the search problem for me, even if question answering were a solved problem.