You do know that every game ever is developed on PC first then ported over to console right? You could make a console game in Unity for lets say PS4 and Xbox One and easily patch both because porting is basically a click of a button in a game engine like that, and assuming because Bungie made their own engine it would more than likely be MUCH easier to patch and port Destiny for every single console because it was designed to be a console only game and never intended to be played on PC. Wouldn't be surprised if it takes them 2 minutes to port everything, the code for this game is the same for every console, which is C#.