I am no expert, but do not necessarily pick apart findings = conclusion as many are.
General rule: anything can happen. It all depends on exactly what happened how things can shape up.
I wouldn’t put it past the plane to include large pieces even with a direct hit. Plunge in perfectly and the fuselage may stay together, as the weak wings tear off. Then the fuselage may disintegrate just after impact.
As to floating on and on, again, it could happen. Airplanes are made to be as LIGHT as possible. Thin aluminum with honeycomb composites. The airspace in some of those honeycomb panels could be enough to allow floating.
I will say, though - how do they know these pix from Aus sat weren’t whales?
http://www.freerepublic.com/focus/news/3135196/posts?page=197
We are very lucky to have pilots, engineers, traffic controllers and other experts as part of FRamily. They were out in full force to help the rest of us last night (The number/letters are handles for air professional network is my understanding. )
Other posts in this area will help people understand. Definitely a thread for FR top archive
The wings are pretty strong. Their interior structure is braced and the metal is usually stronger that the rest of the airframe. You ever see those "no step" areas outlined on a wing? If so then this is thinner material than the wings. If you walk there you would damage the skin.
The strongest part of the jet is the wing box, this has to take the stress of the wings flexing and the impact of landings. In a water landing or gear up landing the engines tend to rip off first.