Hard disagree, this ain't gonna kill CMSs, what are you talking about?! Content management goes beyond just a website, especially in the headless cms world. Also those products can be as low as free.
Been involved with a lot of Contentful projects large and small that only existed to publish content to web properties. I guess it kills that use case.
Depends imo. If it's purely just a few static pages then yeah I can see this happening but as soon as you have anything like a blog you're going to want some sort of content management system surely to manage it?
What I see this more doing is eliminating the need for someone to code the glue between the CMS and the website -- you can just ask the AI to add code to get your blogs from Contentful
