Light and dark end up destroying each other or crippling eachother. We fight Xivu Arath in a flagship above the Last City while the Traveler holds the Pyramids back. New Monarchy, Dead Orbit, Future War Cult, and Black Armory evacuate humanity. We leave the system and see the Traveler and Pyramids nuke each other. Calus contacts us and asks for our help at reclaiming his home world and in advance, tells us of an Athenaeum world humanity and its Eliksni allies can settle on. This all leads to a Destiny reboot or spiritual successor hundreds of years later where Guardians have become myths and humanity has found new tech and power to survive.