First off, we know that Bran's visions are more complicated than they appear. They can take place in the past, present, or future, and (so far, at least) past visions can even be changed , altering history as we know it. It's hard to know exactly what kind of vision we're looking at, however, unless we pay pretty close attention. In this particular instance, writer Joanna Robinson noticed that it looks like the White Walkers are stepping on grass, turning it into snow as they cross. This would have to mean that they're south of the Wall — something that's never happened before. Is this an ominous look into the future? Is Game Of Thrones going to end in some kind of White Walker apocalypse?