I think that this just demonstrates that the wing box area is one of the structurally strongest parts of the aircraft. The forward and aft sections would probably have broken away and sunk after being flooded, while the central part of the fuselage would have been kept afloat by the bouyancy provided by the space in the fuel tanks.
Its good news both engine were recovered which should aid the investigation. Don't know if the recorders were found as well and just as a side note, the depth of the sea in that area quickly goes down to about 1000m.