RSS hasn't gone anywhere. Every podcast my podcast player downloads is announced to it either via RSS or Atom feeds. It has just fallen by the wayside as the way people become aware of updates to websites with serial publication of content (in general: because most people get that information from peer-to-peer link sharing, like Facebook, Twitter, Mastodon, Fark, Reddit, Slashdot, or even this website).

They're not even removing the ability for the browser to render XML. They're just removing an in-browser formatter for XML (a feature that can be supported by server-side rendering or client-side polyfill).