In the Hound's vision, everyone is convinced that he's seeing Eastwatch by the Sea because that's the second-most popular Wall castle, it is right on top of the sea, and it is the castle Jon mentions in this episode asking Tormund to man the Wall castles. But is it really Eastwatch the Hound is seeing?
Here is what the Hound says and was slated to say in the episode after Thoros asks him what he sees, including the line that was dropped from the actual episode but is part of the synopsis on the official GoT website.
http://gameofthrones.com/game-of-throne ... /episode-1 Scroll down and click "Read the Synopsis."
So looking at the map, we can see there aren't mountains by or near Eastwatch. The waves there aren't known to be frozen, as they would be with the Bay of Ice. Note the castle on this western edge of the Wall, Shadow Tower.Ice. A Wall of Ice. The Wall...
It's where The Wall meets the sea. The waves are frozen... There's a castle there. There's a mountain. Looks like an arrowhead. The dead are marching past. Thousands of them.
Map of the Wall:
Here is a Frostfangs drawing, which to me looks like an arrowhead:
So Shadow Tower is a castle on the Wall near the sea where the waves are frozen and near mountains that are shaped like fangs or arrowheads. While it is true that Eastwatch is more on top of the sea than Shadow Tower, we know that Eastwatch is not near mountains and we don't have reason to suspect the Bay of Seals is frozen like the Bay of Ice.
I do believe the Wall will come down, probably at the end of this season, but I wonder if we may have many wights cross the Bay of Ice before the Wall comes falling down.