Assassin's Creed IV: Black Flag aims to change up the series' formula in more areas than just the setting, especially on next-gen consoles.
According to creative director, Jean Guesdon, in an internal Q&A (courtesy of All Games Beta), the next-gen versions of Black Flag will feature connected single-player experiences. "Next-gen versions will bring to the players new, connected features allowing them to feel that even if they remain 'single player,' it will be better to be a 'single connected player,'" Guesdon explained. "I mean that next-gen consoles will allow players to have a solo experience that benefits the presence of a huge community."
Unfortunately, how this might be implemented was not detailed, so all we can do is speculate for the time being. With online connectivity playing such a huge role in games today, this should hardly come as much of a shock. Hopefully it provides an engaging twist on the Assassin's Creed formula rather than serving as a needlessly tacked-on gimmick.