Well, of course.
These days, it's exceedingly rare for a major new release to ship without a multiplayer option. This includes games that absolutely don't need a multiplayer function ('cough' God of War 'cough'), but whatever.
According to a new job listing at Eidos Montreal's website , it seems the new Deus Ex installment will feature an online mode of some kind. The developer is looking for an Online Programmer to specifically work on Deus Ex: Universe , the next-gen project that spans multiple titles and is coming to consoles and PC. The Online Programmer will implement online game features and build a suite of tools as well.
Yep, sounds like multiplayer is coming. It may be revealed when Square Enix announces "Deus Ex: Mankind Divided," which isn't official but the company filed a trademark for that title last week.