I am suprised that the "T" word (terrorism) hasn't been mentioned more often as a theory today?
To be honest, I'm glad it hasn't been. A tiny fraction of aviation incidents are terrorism related, and to go along that train of thought in a case like this is completely unfounded.
Also, it's hardly a terrorist coup to have a plane crash into the middle of the Atlantic Ocean - just devastating to those who have family and friends unaccounted for.