If it wasn't retconned, the Traveler [b]did[/b] try to abandon us. Then it was shot down by Rasputin, forcing it to stay and somehow change it's mind on humanity. Or at least that would've been the plan if the Traveler decided to leave. I've read that quite a while ago in the D1 Grimoire, so don't quote me on that cause it might be outdated and already retconned in D2. Calus says the end is coming, somewhat similiar to Dead Orbit. So I guess we will see that someday. Perhaps he's referring to those Pyramid ships. Or something else. The things he saw at the edge of the cosmos.