Do you mean LLMs will be used to generate more SEO content that is irrelevant?
Doesn't it work both ways? You can use LLMs to filter out irrelevant content better than ever? A lot of the time I use ChatGPT-4 it's as a search engine - and I don't even mean with the Browser plugin, I mean it's quicker to ask ChatGPT-4 for its encoded knowledge than to Google and click on links.