A newly filed trademark may be the first we hear of the next Deus Ex game. Square Enix filed for "Deus Ex: Human Defiance," which obviously bears a striking resemblance to 2011's Deus Ex: Human Revolution. The publisher has not officially announced a sequel.
The trademark application (via CVG), which was filed just yesterday, could be a red herring or otherwise meaningless, but the timing makes a fair bit of sense. Eidos Montreal (a Square subsidiary) is currently consulting on a CBS Films adaptation of Human Revolution. The trademark could refer to said adaptation, but we're placing our bets on yet another game.