There is much speculation and theorising over this incident .. but, in all honesty, there are many more questions than there are answers, and the world's experts are just as confused - but are being sensible and not coming up with the wild suppositions of the media ...
Other than the, sensible, questions asked in the media regarding debris and lack of it, satellite tracking and routing, communication or the lack of it .. etc etc there are the questions that those who know the aircraft, and the "system" are asking .. but are unable to answer ...
1) Every aircraft is fitted with an emergency locator beacon, this is activated by both impact and/or water, and the failure rate is miniscule. It has not been activated - which leads to a lot of questions ....
2) The commonly called "black boxes" - actually bright orange and made to detach and float - also have locator beacons - these also have not been activated.
3) In the event of a total engine failure - an unlikely but possible occurrence - the aircraft would descend in a steep "glide" of around 6000 ft/minute. From 35000 ft that is 6 minutes ... more than enough for a distress call on the battery powered radios
4) In the event of an explosive decompression, or a bomb - the aircraft "falling apart" - numerous items would float .. seats, liferafts, clothing, suitcases etc etc ... nothing has been found
For an aircraft, and 200+ passengers with all their luggage etc etc to simply disapear without trace is, actually, unprecedented.. in every other equivalent mishap there has been some trace of the wreckage......
More questions than answers at the moment ....