I agree with some of the people above me. The first leg of this journey will most likely consist of we the Terrans (assuming the Awoken are some sort of valkyr-esque experiment gone awry and the Exo which show signs of beings that are much more advanced than the servant droids showing us around the Tower [maybe android bodies for Darkness victims]) are fighting our way out of our final bastion to take back our solar system > galaxy > universe. In my mind what we've seen so far and heard is that this is meant to be a very personal and close to home crusade against an unstoppable force and its armies. We alone must become the immovable object.
Remember this IP has already been on record for being one of Bungie's major projects for the next ten years.
Where's the option for: Yes, but not now.