It's not exactly a surprise at this point since Ubisoft's treasure trove of goodies was raided a few days before tonight's Ubisoft Forward and Assassin's Creed Showcase, but regardless, as the announcement is now official, here it goes.
Ubisoft Quebec, the team who brought to life Assassin's Creed Odyssey, under the direction of Jonathan Dumont, is working on a new mainline game in the series, which as of right now is being known simply as Assassin's Creed Codename Red.
It will be set in feudal Japan, and will be an open-world title that was even described as "the future of our open-world RPG games", by Assassin's Creed veteran Marc-Alexis Côté. Otherwise, details for the game are currently very scarce, but we are told that players will play the role of a shinobi within the game.
As for when Codename Red will actually debut, the roadmap for Assassin's Creed as a series notes that it will likely be some time after 2023, but Ubisoft hasn't actually provided any dates or time frames relating to launch as of yet.