If that is true, I don't understand the move up to 45,000 feet (ie above the aircraft's design limit) and the 40,000 foot drop.
It's best for the families if it was a hijack. That leaves some small hope of a secret landing some place. But to do this with this degree of planning and sophistication (ie disappearing a 777) means there can only be one organisation which is responsible.
If it was the pilots, I wonder if they were hypnotised.