Most likely increase, despite your intuition. This argument has been debunked so many times both intellectually and empirically. For one, read "Against Intellectual Property" by Stephan Kinsella.
That being said, in this scenario of yours, how much of that additional work do you figure would be actually original? If someone wants to make a living with music, why bother learning an instrument and writing songs if nobody can stop them from just recording someone else and selling that?
That's really the heart of this lawsuit, isn't it? If we give freeloaders the right to legally monetise other people's work, we will drown in bland, derivative, stolen garbage and drive out the actual creators, in the process also breaking the "business model" of the freeloaders. A real lose-lose-lose situation which I see as much more realistic and believable than Kinsella's libertarian dream world.
Not much need for extrapolation, either. We can just watch it happen right now. "Content production" on the web is definitely exploding, as per your point. But even in the mainstream, most people will agree that this flood of new, LLM-generated "works" is worth less than the originals they're sloppy pastiches of.