My experience in the publishing world is that there is already an infinite supply of writing. Lots of things serve as filters, some for better and some for worse, but ultimately the quality of the writing (however we define that) vs. the field is part of that filter. There is a competition for our limited little attention spans and finite waking hours, and writing better suited to our tastes tends to win out.
I don't see how that dynamic changes with AI. If all writers have more or less equal access to AI, some writers will use it in ways that result in writing I enjoy more than others. Some won't use it at all and still write work I really like. The majority of people writing with or without AI, just as today, won't write stuff I really want to read.
I don't know if I've ever read a piece of SEO-driven content marketing and thought it was particularly profound or that it made an impact on me. Or that I really had an inherently meaningful connection to the author. I sort of don't care if people generate 100x more of that sort of thing. It makes Google searches less effective, I guess? Or it may make my For You Page on Instagram less human-rich?
I've read some nice poetry though. I usually go looking for it. There are a handful of authors I tend to like consistently. The overall volume of poetry published (it's quite a lot!) doesn't really have an effect on my preference for their work. If there was 1,000,000 times more poetry published because of AI, I don't think it would prevent me from seeking out new poems from writers/publishers/curators I like, nor would I probably really notice.