I believe the wording was "floating in the air" or such on the limited multiplayer =) (trading for example).
So it's not planned currently for the limited multiplayer, but time will tell.
Regarding full multiplayer: The game is not designed to be a multiplayer experience and it would present a lot of new problems to solve, not to mention the amount of work regarding implementation. All of this time would be out of time that could be spent on the core features of the game. So yeah, heavily leaning towards creating the best single-player experience we can.