After watching and rewatching the official trailer at the end of the stream I have been doing some thinking on how this update could possibly be related lore wise to Destiny. I believe that our current story is over for now. We pushed Atheon off his pedestal. We unplugged Crota's network cable. We obliterated Oryx with 16 of his own bombs. We even spun at the feet of Axis with Darkdrinker. We have pushed back the darkness as far as we can. These stories of our heroics are spreading. Children are telling each other of the noble Warlocks, agile Hunters and strong armed Titans that have been protecting them all of these years. After the next update we are no longer MAKING the stories we are the characters IN the stories these children are telling. The path up until D2 comes out we are no longer in the real world. All of that is over. We are now playing in the dreams and the stories of the children of the last city. Bare with me a moment before you stop reading.
Our light level is remaining at 400. No further progress is being made. We are venturing back into the Vault of Glass, Crota's End, King's Fall, and Wrath of the Machine. All of which are unchanged with exception of maybe some cheese being removed, but who hasn't heard the same story 3 different times from different people and a few of the facts have changed a little? All of our old wonderful weapons will be obtainable because you can't have a story about the Vault of Glass without exploding Vex due to our trusty Fatebringer or firing through the Knights shields in Crota's End with our Oversoul Edict. Vault size is staying the same, vendors and other characters are staying the same as well. Nothing is necessarily being added with exception to a few minor improvements here and there on gear, drops, sparrows, ghosts and such. All those little improvements are just embellishments of a child's story. We are going to be playing as the characters of the stories we helped create.
TL;DR: Destiny 1 is over, no more lore is being added, Age of Triumph is putting us in as the characters of a child's story about the things we have already accomplished.
EDIT: Bad youtube link. Thanks /u/donball !