Wrong. The low-quality content farm will be out and the high-quality site will be fully paywalled (no more data to AI).
For instance, when searching for information on setting up RDS, like high availability MySQL on self-hosted servers on-premises, neither ChatGPT nor Brad provided the necessary details. I would not make a publicly searchable blog or Github repository if I were well-versed in setting such RDS on-premises. Instead, I would make it available only behind a paywall. Why should Google and MS/Bing benefit from my hard work if they do not direct traffic to my site? Previously, low- or high-quality pages benefited from SEO, but that is no longer true. There is a wealth of knowledge that has not yet been documented. Unless Google or Bing starts directing many traffic, experts, and websites will not share updated and other valuable information. I anticipate more paywalls for high-quality content, similar to good news sites.
Besides that, be careful about wishing for one or two centralized sites controlled by big tech giants with AIs such as Google and Microsoft. The web developed because of many 3rd party websites.
I don't have answers on how good 3rd party sites will survive with Google/Bing sending traffic and Ad clicks, but the equation is about SEO changing. Either you create non-profit Wikipedia-style content or high-quality content paywalled. That is my best guess.