Chris Scott
There have been discussions about this elsewhere. The questions are about things like how rough the sea might have been - weather reports say calm. There are also questions about how much control the automatic flight envelope protection systems might have had over the final trajectory.
It is one thing to say that it is unlikely that the aircraft remained substantially intact but quite another to say it is impossible.
Subsequent to the touchdown there are questions about ocean winds and currents and locations where debris might eventually wash ashore. I have read suggestions by people who know more than I do that wreckage may drift for many months - even years - before washing up. The possible locations are affected by the range of possible impact points but may be as far apart as South Africa and Tasmania. Since the impact point is unknown and all of the searches to date may have been distant from it, I don't find it surprising that no wreckage has been identified. The Ocean is vast and the possibility remains that very little floating wreckage might be present.