There is a lot of overall creative ways. Earth gets taken by the deep. Certain darkness based on certain parts. Earth doesn’t get taken, but a massive armada or even bigger planet shows up and we are now operating into the darkness planet. Traveler leaves like before, darkness ensures it finally catching its prey. We invade the traveler itself, now tainted, and attempt to reclaim it. Take your pick. That’s just covering the ones where it makes it to earth.