- I still think that the probability is a bomb hidden on the plane and timed to go off when it was over the ocean so as to ensure as few survivors and as little remaining evidence as possible.

- Another theory is that it was a terrorist take over of the cockpit to force the pilot to change direction and head for a major Asian city for another 9/11 type of attack against a landmark skyscraper but that the terrorists were overpowered by the crew and passengers and/or the pilot bravely chose to dive for the drink rather than to kill thousands of people in the destruction of the intended urban target.  Since the ultimate mission failed, this might explain why no terrorist group has come forward to take responsibility for it. 

- In any case, the longer it takes to recover any evidence the more likely it is that we'll never know what actually happened and who was involved.