I can only speak for myself, but a Metaverse consisting of infinite procedural slop sounds about as appealing as reading infinite LLM generated books, that is, not at all. "Cost to zero" implies drinking directly from the AI firehose with no human in the loop (those cost money) and entertainment produced in that manner is still dire, even in the relatively mature field of pure text generation.
IMO current generation models are capable of creating significantly better than "slop" quality content. You need only look at NotebookLM output. As models continue to improve, this will only get better. Look at the rate of improvement of video generation models in the last 12-24 months. It's obvious to me we're rapidly approaching acceptable or even excellent quality on-demand generated content.
The fidelity of a video generation model is comparable to an LLMs ability to nail spelling and grammar - it's a start, but there's more to being an author than that.