One possibility is that the story delves deeper into the history of the Jedi and Sith. Cal could discover some long - lost secrets that have the potential to change the balance of power in the galaxy. He may also have to deal with the remnants of the Empire that are still trying to hunt down any remaining Jedi. His training could reach new levels as he learns from different sources, perhaps some ancient Jedi texts or even from the Force itself in unique ways.
Well, it might continue Cal's journey in exploring more of the Force mysteries. Maybe he'll face new and more powerful enemies, like some ancient Sith lords. He could also travel to new planets to find hidden Jedi knowledge.