The Game of Thrones season seven poster promises ice, fire, and nothing else

In an age of teasers that spoil the entire plot before the movie or show is even out, Game of Thrones’ season seven poster is impressively restrained. Where previous series posters have hinted at a character’s ascension, or promised long-awaited plot points, the newest example tells us only two things — there will be fire, and there will be ice.
Feel free to speculate from there about exactly what the union of fire and ice could mean. Does that mean the dragons will cross the n