IANAL, but recently I've become very interested in the possibility of a legal mechanism a bit like what the GPL does for code [0], a kind of poison-pill so if anybody uses your content to train their LLM, you can slap back by making everything that LLM ever emits into almost public-domain [1]. In other words, you strike 'em where it hurts, in the monetization.

[0] https://news.ycombinator.com/item?id=42582615

[1] https://en.wikipedia.org/wiki/Public-domain-equivalent_licen...