I would say it's not reasonably likely that LLM training is fair use. Because I've read the most recent SCOTUS decision on fair use (Warhol), and enough other decisions on fair use, to understand that the primary (and nearly only, in practice) factor is the effect on the market for the original. And AI companies seem to be going out of their way to emphasize that LLM training is only going to destroy the market for the originals, which weighs against fair use. Not to mention the existence of deals licensing content for LLM training which... basically concedes the point.
Of the various options, a ruling that LLM training is fair use I find the least likely. More likely is either that LLM training is not fair use, that LLM training is not infringing in the first place, or that the plaintiffs can't prove that the LLM infringed their work.