Although Ubisoft has yet to officially announce the next DLC pack for Assassin's Creed Revolutions, it's already been detailed, priced, and dated. The upcoming single-player add-on is likely the last extension of the franchise, before October's release of Assassin's Creed 3.
According to Major Nelson, the add-on will be available on Xbox Live on February 28th. A PlayStation Network and PC release is likely to land on or around the same date. It will be available for 800 Microsoft Points ($10).
Leaked achievements show that the DLC will continue Desmond's odd first-person platforming adventures from the retail game. Given Assassin's Creed 3 is supposed to conclude his story, this DLC will likely include many teases for what to expect from the "trilogy's" finale.