CD Projekt Red has said it will focus its efforts entirely on the Cyberpunk 2077 and Witcher series, while also reaffirming that it wants to develop more games in The Witcher universe.
In a discussion with journalists recorded by Polish business site Stooq (and translated with Google Translate), CD Projekt Red president Adam Kicinski said the studio was already working on another singleplayer game and that it had a "relatively clear concept."
That said, it will be a while before the bulk of the studio's resources will be moved to it: after the release of Cyberpunk 2077 in September, Stooq reports that the largest team will move to Cyberpunk 2077's multiplayer component, while the second largest will work on the game's singleplayer expansions. A third, smaller team will work on "another large singleplayer game."
Based on Kicinski's statement that CD Projekt plans to continue working in the Witcher and Cyberpunk universes, a new Witcher RPG seems likely. From what CD Projekt has said in the past, though, it probably won't be called The Witcher 4.
During the same interview, Kicinski also discussed the potential for COVID-19 to impact Cyberpunk 2077. "The situation regarding coronavirus is so dynamic that it is hard to think about it. We will take part in trade fairs, if they take place. If they do not take place, we will show the same things in a different way - the internet works normally, we have a way to reach players."
I've reached out to spokespeople for CD Projekt Red for clarification, and will update the story if I hear back.