I used to teach high school. When a kid handed in writing that was not their own it was obvious. If anything, AI will make it more obvious and thus occur less often.
I've been taking some online classes these last two semesters, and I can cleanly group my classmates into three categories: the blatant LLM users, the rare students who actually invest themselves, and the majority whose contributions are so cursory that it hardly matters whether they wrote or generated it.