User blog comment:Master Sima Yi/Assassinews 10-05'12 — World Gameplay Premiere/@comment-188.222.224.194-20120513142412/@comment-4975789-20120513180356

They said that Desmond's story concludes with AC3, so after this there's no more Altair, Ezio or Connor (unless if they use someone related to Desmond or the ancestors e.g. Subject 16 and Ezio).

I expect that if they release a Desmond trailer/teaser, it'll be at E3 at the start of June.