That is NOT a possibility, the culprit would have spoken out and admitted it.
Talking to my dad, who is a captain for emireates on the a330, a340 and a380, and also trains new crews on flying the A 330, he put across the theorys on what has happened and also the course of action being take at the time
Theory 1- Fire . As has happened beofre, if a fire happens to start in the cockpit or anywhere else in the aircraft, probably due to the electronical failiure previously stated, many things could happen. Such as the pilots being un able to fly the aircraft due to the fire, the fire bruning through electrical cables (The a 330 has all cabules for control input in the underbody of the aircraft, and although their is one main line and a backupline, if the fire was to burn through both all control would be lost) Now although this is a theory worth considering, if the fire was to burn through the two control cables the aircraft would keep flying untill it ran out of fuel, and by that time it would be somewhere over africa, not the atlantic.
Theory 2- Storm. Not very likely, air france pilot are trained to a very high standard, if they saw a big storm they should fly around it. Lightening is DEFINATLY not the cause, ligtening hits planes, and exits straight away. The only thing that could of made the aircraft break in a storm up is hail or extremely severe turbelance, very large hail, we are talking soccer ball sized hail here though which is entirely possible at that altitude.
Theory 3- Breakup. This is the most possible theory in my dads eyes. Something similar to the turkish airlines Flight 981 crash in march 1974 is entirly possible (
http://en.wikipedia.org/wiki/Turkish_Airlines_Flight_981). What broke off we dont know at this point, it could be the cargo bay door like the Flight 981 disaster. Also, for some reason the Airbusses control cable layout is the same as the Dc 10's (The aircraft in the Flight 981 disaster), Coincidence? If so, airbus needs a re think.
Theory 4- Crash landing. It could still be out their, floating on the sea, whos to say for some reason all electronics failed, for some reason they couldnt transmit a Mayday or put out an EPIRB, they could be out their, waiting for rescue now.
Now we come to whats being done, its entirely possible the aircraft is not lost, yet if it is the first thing we need to find at the blackbox, only thing is, blackboxes dont float, were going to need a submarine to get it. The search is underway, once the blackbox is found all will be revealed.