It'd be cool in the later games to have a story where our ghosts start becoming corrupted with whatever, which in turn affects our character like a disease. As it gets worse, we'll be granted really dark/evil type supers, melee abilities, and whatnot as well as really ancient armor. (I'd like to see some Speaker type armor, but evil) Then as we progress we have to fight off whatever is corrupting ourselves and our ghost. Maybe having to retrieve some sort of program or bring our ghost to some otherworldly tech planet or maybe into the Traveler. I don't know man. Just something I thought up on the dot lol.