Well, nobody's really sure. It could be that Cancer is making them have visions of the past, or maybe Snippy's having dreams of the future. Or maybe he's just having irrelevant dreams and none of this ever really comes true, though I doubt Alexiuss would go for that route. The fact that Snippy's acting in the past based on his dreams would point to it being the dream-route, but who knows.
Well, Vitally knows, of course, so I guess we'll just have to wait.