Asked by Outside Xbox if there'll be any delay between the release of the current and next-gen versions of the game, Ubisoft Montreal's Jean Guesdon simply replied: "Same ship."
It is possible Guesdon's comment has been misconstrued, and that he simply meant that development of the next-gen versions will be completed alongside the other editions, in time for whenever Sony and Microsoft opt to launch new consoles.
However, it's worth noting that he was specifically asked: "Is there going to be any delay between the versions, or are they all going to release at the same time?"
Ubisoft has officially announced an Assassin's Creed 4 release date of October 29 in the US and November 1 in the UK on PC and current gen consoles.
Sony has confirmed a PS4 release date of "holiday 2013" in at least one of Japan, Europe and the US.
Guesdon also recently said that, "in addition to improved graphics and physics", next-gen versions of Assassins Creed 4 will offer enhanced connected features, although he was vague about their exact nature.