An Ubisoft representative told GameSpot, "We have nothing to share at this time."
Watch Dogs and Assassin's Creed IV: Black Flag are confirmed for PlayStation 4, while Ubisoft has teased that the latter is slated for "next-generation platforms." [Emphasis added]
Both games are also in development for current-generation hardware, including Xbox 360, PlayStation 3, and Wii U, as well as PC.
Microsoft is rumored to announce the Xbox 720 during an event on May 21.