Square Enix hasn't announced a sequel, and Human Revolution developer Eidos Montreal is understood to be working on an unannounced third project that's "alongside" the Deus Ex and Thief franchises. Straight Right, the Mass Effect 3 developer for Wii U, is reportedly porting a major Square Enix game to the Nintendo console, and if that's accurate Human Revolution is a contender and Human Defiance may relate to that.
At this moment, however, Square Enix has kept any upcoming entries in the Deus Ex franchise as stealthily hidden as Adam Jensen in an air vent - perhaps until now, that is. We've reached out to the company for comment.
Update: A company representative tells us, "Square Enix does not comment on rumor and speculation."