To me, the greatest threat is information pollution. Primary sources will be diluted so heavily in an ocean of generated trash that you might as well not even bother to look through any of it.
And it imitates all the unimportant bits perfectly (like spelling, grammar, word choice) while failing at the hard to verify important bits (truth, consistency, novelty)
I see that as the death knell for general search engines built to indiscriminately index the entire web. But where that sort of search fails, opportunities open up for focused search and curated search.
Just as human navigators can find the smallest islands out in the open ocean, human curators can find the best information sources without getting overwhelmed by generated trash. Of course, fully manual curation is always going to struggle to deal with the volumes of information out there. However, I think there is a middle ground for assisted or augmented curation which exploits the idea that a high quality site tends to link to other high quality sites.
One thing I'd love is to be able to easily search all the sites in a folder full of bookmarks I've made. I've looked into it and it's a pretty dire situation. I'm not interested in uploading my bookmarks to a service. Why can't my own computer crawl those sites and index them for me? It's not exactly a huge list.
It’s already been happening but now it’s accelerated beyond belief. I saw a video about how WW1 reenactment photos end up getting reposted away from their original context and confused with original photos to the point it’s impossible to tell unless you can track it back to the source.
Now most of the photos online are just AI generated.