The confirmation comes to us by way of the cover for the December issue of Game Informer, revealed earlier this morning. As such, there's not much in the way of detail, although it did say that the game will be set in a fictional Mediterranean archipelago, the parachute and grapple have been "vastly improved," and that players will be able to take the skies in an all-new wingsuit.
One thing it doesn't mention is whether or not the game will feature microtransactions. That became a question earlier this month, when a couple of leaked screens allegedly from the game indicated that players will be able to rent or buy vehicles and weapons with "diamonds" that can be purchased through real-money transactions.
Just Cause 3 is currently expected to come out next year.