User blog comment:D. Cello/Assassinews 03/05 -- ACWiki's Fan Section and AC3 first trailer/@comment-4374396-20120312184300/@comment-4374396-20120312230755

I don't think that it's officialy confirmed, but it's almost sure he will be in the game. Yeah, so far Brotherhood was the game where Desmond had actions. Since it's his last game, I don't see how Ubisoft could let us down.