I don't think they might even announce about that game even if they are planning to make it, they keep postponing the release of Cyberpunk and I am sure they will do it again, so I don't think we should discuss The Witcher 4, we should talk about the cyberpunk new release date LOL
I heard rumors - just rumors - they consider another game in this world, but not with Geralt. His story is told.
If this is true, I'd love to play a Vesemir-Prequel, when the witchers were way more and there was a real academy in Kaer Morhen.