https://blog.arxiv.org/2025/10/31/attention-authors-updated-practice-for-review-articles-and-position-papers-in-arxiv-cs-category/
Centrailzed publishers won't go away for a long time since they hold exclusive rights to groundbreaking works for at least 70 years after the deaths of all authors. That's a different story.
But for (new) preprints, that's not the case. In the past, a centralized system was somewhat useful for content discovery. But with standards like ActivityPub, that's no longer necessary.