****If the plane hit the water at terminal velocity or under power, the cabin would not have stayed intact. That would be a physical impossibility.****
Chesley “Sully” Sullenberger says you can land a jet in water in one piece.
Sully did a controlled landing, at a level attitude to the water.God bless him. He was probably one of the few pilots in the country who could land that plane that way without flipping it. A remarkable feat.
A plane falling from the sky without control is not going to glide to a landing. It is going to head in. Even a flat spin landing would just about destroy the plane on impact.
Although a 777 can fly, it is a heavy beast when no longer airborne.