I certainly think he's building his army. I think many expected the battle to to continue into the water given Cotter Pyke's letter to LC Snow in the novels where he says dead things in the water. I half expected a crap load of dead things to rise out of the sea when the NK began to raise his arms. Since I was pretty sure Wights just came back to life without his direct influence but obviously that increased the impact of the scene. One can only begin to imagine what happens if they ever get south of the wall. Our protagonists will be battling the kings of winter and such.
