I'd tend to agree. I said we may have that, and then he might have a point. But, if we don't, he'll be wrong because current LLMs aren't going to (I think at least) get past the limitations and cannot create anything close to original content if left to feed on their own output.
I don't think it's easy to say what will be the situation in 15-20 years. The current generation of AI is moving ridiculously fast. Can we sidestep to AGI? I don't know the answer, probably people doing more work in this area have a better idea. I just know on this subject it's best not to write anything off.