The Next Wolfenstein Game Will Be Wolfenstein: Youngblood
At Bethesda's E3 Showcase, MachineGames creative director Jens Matthies took the stage to talk a little bit about the upcoming Switch port of Wolfenstein II: The New Colossus before revealing that the next Wolfenstein game was already underway. The next game is called Wolfenstein Youngblood. Matthies revealed that the game would be co-op and focused on BJ and Anya's twin daughters, who will star in the game.
Scenes during the trailer suggests that the game is set in the 1980s, with Matthies saying it takes place in Paris. It's worth noting that a "III" is conspicuously missing from the title, suggesting that this could be a spin-off and not necessarily the third game in MachineGames' trilogy.
No platforms have been revealed for Youngblood yet.