Whilst I will not speculate on what may have happened, I hope that this event will expedite the worldwide coverage of Automatic Dependent Surveillance (ADS) , especially in Oceanic areas where VHF radio and normal radar is non existent. This would greatly assist the search and rescue operations, especially if there are survivors involved.
Whilst it is unbelievable in this day and age that a modern aircraft like the A330 would disappear whilst airborne, it is more unbelievable that the last exact position of the aircraft is not known. All of us aviators should push for the worldwide coverage of remote areas with ADS and other satellite based monitoring.