I recently built and delivered an AI-driven novel-writing program. The architecture involved chaining the Claude, GPT, and Gemini APIs together so they could cross-critique and iteratively revise the text, while systematically saving key plot points and lore chapter-by-chapter. (Serialized 'web novels' published on a per-chapter basis are a massive industry here in Korea). AI has already heavily infiltrated the fiction space in Korea, and it looks like the exact same trend is hitting the US.
Personally, I find it incredibly easy to spot AI-generated text in Korean, but catching it in English is much harder for me. That being said, they still have very distinct, overused patterns. You constantly see words like 'ultimately' or 'structural,' and they rely heavily on highly formulaic 'X is Y' sentence structures.
I actually think there's going to be a big industry there, and right now, it's just mass-producing slop to exploit not-very-discerning publishing channels, but eventually an AI pipeline that can churn out mediocre, but extremely personalized one-off novels and stories on demand will be a real business.