I think LLMs could provide attribution. Either running a second hidden prompt (like, who said this?) or by doing reverse query on the training dataset. Say if they do it with even 98% accuracy it would probably be good enough. Especially for bits of info where there's very few or even just one source.

Of course it would be more expensive to get them to do it.

But if it was required to provide attribution with some % accuracy, plus we identified and addressed other problems like GPL washing/piracy of our intellectual property/people going insane with chatbots/opinion manipulation and hidden advertisement, then at some point commercial LLMs could become actually not bad for us.