In an interview with AusGamers, Animation Director for Ubisoft Montreal, Australian David Wilkinson, let slip an interesting detail about the next instalment of the Assassin's Creed franchise.
When asked about Alex Drouin, Animation Director on Prince of Persia: Sands of Time, he greatly complimented his work, before giving away that, "He's busy making Altair even more beautiful. Last thing I saw him do was getting Altair to swim." It's not much to go on, but from this we can gather that the next Assassin's Creed is being worked on, that it will indeed feature Altair in some way (a more beautiful Altair at that), and that he will in fact be able to swim, unlike the original game where he drowned upon contact with water. Could Altair be prettying himself up in preparation for some aquatic assassinations?