Until people on the forum started talking about wanting competitive multiplayer, I don't remember multiplayer being mentioned anywhere. Co-op, yes, but not multiplayer. It wasn't part of the goals or the game during the KS, and there hasn't been any indication from the devs that it will be put in before or after release. They did say that the engine would let up to 6 people play together if you made a campaign or mod that allowed it, though.
