Finding and tracking these rogue planets today seems to be a bit like the astronomers of old figuring out the movement of planets in our solar system. It'll probably be very useful in the future. Maybe one day we might even be able to adjust the course of one of them.

Related to this, I wonder what the minimum resources a rogue planet has to have for human habitation in the future. Obviously there won't be sunlight, which means that we will have to generate all of our energy in some other way. Nuclear fission? Fusion?