>produce convincing sounding output
Well, correctness(though not only correctness) sounds convincing, the most convincing even, and ought to be information-theory-wise cheaper to generate than a fabrication, I think.
So if this assumption holds, the current tech might have some ceiling left if we just continue to pour resources down the hole.
How do LLMs do on things that are common confusions? Do they specifically have to be trained against them? I'm imagining a Monty Hall problem that isn't in the training set tripping them up the same way a full wine glass does