I believe that the next DLC will be Cabal/Vex. The Vex travel to Earth, and fighting them off, us Guardians accidentally kill a time lord that takes the city out of time. We eventually get it back into our time, but a century has passed and the cabal have taken control of Earth. We then go on a kill fest, only to learn the big Cabal commander is on Earth. We travel to a new place on earth(Africa, U.S., S. America, etc.) and kill him in a new raid.