There is a Strugatsky brothers short story, in which most of the inhabitants of a planet seem to have suddenly left via some portals, but there are a few who remain, highly armed, violent, and apparently seeking to prevent anyone else from using the portals.<p>TFA reminds me of this story (which reminded me of the situation sketched by TFA when I had read it, except perhaps for the ratio of leavers to left behinds) but I cannot recall its name?