Just had a thought for a Destiny 2 premise ... what if the strange coins the Nine are collecting are quantum recordings of Guardians ... each of them a recording of a moment of bravery that would allow a Guardian to be brought back? And then ... possibly the Nine have through the Vex acquired the ability to send this force of Guardians back in time to the time of the Collapse, to try to change history and avert the end of the Golden Age. That would allow a new setting and a complete reboot of the game.