Via The Skeptical Libertarian, I just watched the video below about "Laniakea: Our home supercluster." As I pointed out in a comment on the TSL Facebook page, what's really important here is that we now know where to build the border fence as we don't want immigrants from the Perseus-Pisces supercluster sneaking into Laniakea and taking our jobs or sullying our culture.
In all seriousness, though, what will appropriate immigration policy be if (when?) we make contact? Suppose we make contact with an alien race that has mastered interstellar travel, and we welcome them with open arms. We also make contact with intelligent life on Mars, and the Martians object that we shouldn't welcome aliens from another star system into our solar system. To what extent would they or wouldn't they have an argument?