Developer CD Projekt Red has officially announced (https://thewitcher.com/en/news/42167/a-new-saga-begins) the next game for The Witcher series. It states that the next game is currently in development and will be “kicking off a new saga for the franchise”.
The announcement doesn’t reveal anything about what we can expect from the game or when it will be releasing. The team has announced that this new game will not be using the REDengine, they currently plan to be using Unreal Engine 5 to develop it. It’s the start of a “multi-year strategic partnership with Epic Games” with the primary goal of helping to “tailor the engine for open-world experiences”.
CD Projekt Red expands on this slightly on the developers official forums (https://forums.cdprojektred.com/index.php?threads/a-new-saga-begins.11101351/ ). It states that the team has no intention to make the new game “exclusive to one storefront”. This should please fans of The Witcher series who would rather purchase the game on Steam or GOG instead of the Epic Games Store.