I was reading an article in The Times this week by an "expert" whose favoured two theories were hijacking and suicide, so it seems suicide is back on the possibility list? The cockpit security issue again?there are a few theories. It's very well planned, night flight, normal air corridor, shadowing another big plane, Lithium batteries, highly skilled Chinese engineers working from Freescale semi. etc.
The worst scenario involves a mad pilot, after switching off the transponder, he reprogrammed a suicide route into the flight computer, then brought the plane up to 45,000ft, depressurized the plane to kill all passengers quietly, then brought the plane down to 15,000ft, opened door, jumped off air plane etc.
He is now hiding in the Turks & Caicos Islands under a false name.
Regarding the satellite imagery, I reckon there will be a lot going on behind the scenes that we are unaware of, after all this is a very sensitive area of photography.