Some earlier posters have implied that if MH370 ditched under control then it would have broken up on contact. This is not true. FAA certification requires that an aircraft can survive a ditching.
Fact Sheet ? FAA Regulations on Ditching
Regulation 25.801(b) states "Each practical design measure must be taken to minimise the probability that in an emergency landing on water the behaviour of the airplane would cause immediate injury to the occupants or would make it impossible to escape".
25.801(c) states that the ditching behaviour must be investigated by model tests.
When I joined BOAC over 45 years ago we had to watch a film of the VC10 certification ditching trials. They were carried out in a large tank which was normally used for designing ships.
There have been several survivable airliner ditchings in the past. If MH370 was ditched then it will be intact on the seabed.