Call me crazy, but I'm not convinced this is just a huge window or glass wall. Normally, these large glass areas on a ship have supports for the panes of glass—look at construction photos of Eden on the aft of Celebrity's Edge-class ships, 270 on RCI's Quantum-class ships, or the wall of glass in the atrium of CCL's recent Excel-class.
This framed opening on Icon looks different. I'm not sure what it's for, but we may be looking at something more than just a window.