While the announcement has been made official and game engine listed, actual release date details and even the name are unknown at this time, but CD Projekt Red is working on the next installment in the Witcher series. Whether this ends up a full blown Witcher 4 or something else is unclear.
This latest chapter comes with the tagline "a new saga begins" and also features what appears to be a cat medallion. Fans will know Geralt was the White Wolf from the school of the Wolf and appropriately styled Wolf medallions. So this game will apparently take us into the School of the Cat. Other than a single side quest in Witcher 3, the School of the Cat is unknown to myself and largely left out of the games, so this should provide the CD Projekt Red team plenty of freedom to explore this saga in a couple of different ways or perhaps even a couple of different timelines.
The big news on the technical front is that CD Projekt Red is ditching the REDengine (which has powered the game and expansion since Witcher 2) for this installment and instead going with Unreal 5 to power the game. Hopefully that will pay dividends in production, letting the devs concentrate on the storytelling at which they are truly excellent and away from technical limitations of their tools which may have led to the whole Cyberpunk debacle, who knows?!
Speaking of which, for those of you like myself still anxiously awaiting the next-gen update of Witcher 3: Wild Hunt, well, there's still no new concrete information that I've seen on that front, but hopefully we're still on pace for a release sometime this year? So, still waiting there...
You can check out the CD Projekt Red blog post for yourself here: https://thewitcher.com/en/news/42167/a-new-saga-begins