User blog comment:Master Sima Yi/Assassinews 08-02-'13 — Next game will be all new, plus DLC promotional material/@comment-66.189.28.181-20130210162407/@comment-1153722-20130211142334

This is why there is no canon DLC.

And I don't really compare it to Revelations. At least Ezio did not stand out in Constantinople, and with the release of The Secret Crusade beforehand the plot was not so random. I don't think there will be a book about all other Assassin Brotherhoods sending SOS's to other Assassins.