Speaking to VideoGamer, Avalanche producer Andreas Thorsen has stated that the decision to go ahead with Just Cause 3 is entirely down to the publisher Square Enix, as they own the IP. He does underline that they would very much like to continue to work with the franchise, though.
Asked about why multiplayer has not yet been included in the series, game designer Axel Lindberg says: “It would have been awesome but it’s quite complicated technically to do. So that’s the big reason why it’s not in there.”
“Now we’ve gotten our head around and our code basis is now more compatible with online and multiplayer type gaming so it’s a good first step. Just Cause would be awesome in multiplayer.”
Right now though, the developer is busy with other projects.