End of human internet is far-fetched.
LLMs won't destroy human thought since LLMs are an average approximation of human thought. Sure, this might elevate those who are fresh and are just looking for generic copy, though the best writers are secretly just the best thinkers, as writing is a medium to exercise thought.
I'm a bit biased, having built an AI writing tool myself (https://zenfetch.com), though it's for this very reason that we aren't interested in generating new content on your behalf. We simply want to make it easier for you to recall information to augment your work.