Can i surmise that a flat spin is possible, but highly unlikely.
So, what are the chances that there was a multiple instrument failure on board 447. if this was going on, what are the chances the pilots forgot the most important thing...... Fly the plane.
Did they get carried away with progressive faults and didnt notice the aircraft was in a steady descent for a number of mins, only for it to become more critical at lower altitudes. Did they only realise how low they were when they heard the "terrain, pull up" alarm (various accidents have been attributed to pilots worrying about minor faults, and fogetting to fly the plane). Would this result in them pulling as hard as they could on the stick, resulting in the plane trying to climb out, only to hit the ocean at a worrying speed and angle.
Not passing judgement on the aircrew, just offering up another suggestion.