The only thing we know for sure is that the triple 7 is somewhere on planet earth, either in bits (more likely) or in one piece (very very unlikely)
Apparently no distress call was heard and it disappeared in next to no time.
So what would bring down a large airliner with such rapidity that no distress call was made? Here are some options..whether they are applicable to this accident... i have no idea!!!!!
1) Shot down. This may account for the silence, confusion and/or lack of willingness to divulge too much information.
2) Mid Air collision. This is possible if it happened to be with a UAV in this case as there have been no reports of any other missing aircraft.
3) Structural Failure leading to in flight breakup. Another possibility such as a cargo door opening in the cruise or the loss (detachment) of a control surface maybe. Rupturing of a pressure bulkhead might have the same consequence as seen before or a few other possibilities...stress cracks etc. An initial failure would cause the crew to deal with the failure first, to bring the aircraft under control, this then may result in a manoeuvre to get back home... and then the secondary effects or additional breakup renders the aircraft uncontrollable. This may explain a non communication scenario as in Aviate, Navigate, Communicate. Contrary to what non pilots may think... the first action of any pilot in a non normal event is to control the situation, not bang out a distress message, verbally or otherwise.
4) Flight Control Issue. Ive never flown a FBW aircraft so "put this out there" IF a control surface separated, what would the computers do? If the right aileron (high speed or low speed) detached, for example, during a left turn, how would the computers compensate?
5) Bomb on board. Again possible but difficult to do with the amount of security these days....but then how secure is this region?
6) Hi Jacking. Possible... especially if it was bungled and went wrong... such as a fight breaking out in the FD, AP tripped due to unintentional force applied on the stick... A/C goes off in its direction whilst the melee ensues and A/C hits the water. However the supposed communication with the aircraft might debunk this myth.
7) Crew incapacitation. This would only really be likely if another inexperienced or flightsim champion person tried to hand fly the aircraft instead.
8) Terrorist attack. In association with 6 above, Terrorist decides to commit suicide. Possible. He (she) gains access to FD, knock out Capt and F/O and push hard on the stick.
9) Crew Suicide. Possible but unlikely i would to suggest.
Im sure there are a few more potential failures that would have the same effect.
I think descending down to 500 feet and flying to some remote island to land is rather unlikely. I wouldn't want to do it during the day, let alone at night!!!