Ubisoft's Yves Guillemot has confirmed that there's two Assassin's Creed games set to launch in fall of this year. Given that one of the games has already been confirmed as Assassin's Creed: Unity, it's not a massive leap to assume that the other is Assassin's Creed: Comet (or whatever it's going to be called), the old-gen release that's rumoured to be a sequel of sorts to Assassin's Creed IV: Black Flag.
Details regarding Comet are unclear. Earlier reports suggested a 1758 start date and a return of characters like Haytham Kenway (from Assassin's Creed III) and Adewalé (Black Flag), with players set to take control of a Templar called Shay.