Yes I was thinking it seemed like a lot of trouble to go to steal a plane full of (presumably now dead) passangers. Wouldn't it just be easier to steal one off the tarmac on the ground? But then it would be much more obvious that it was terrorism and the plane would be stopped/shot down for sure.
Still, if this is terrorist activity which it certiainly does appear to be, then it seems strange that no-one has owned up to anything yet, which makes you think there is more to come.
On the other hand, I do think this could be one of those things that we never get to the bottom of, never hear the real story and the plane is never found at all.
I don't think Violia's theory about the plane being taken over and flown like a drone quite holds water. You can fly an un-manned military drone from the ground because it is designed to be flown like that, but these 777's don't have those kinds of automation systems. Sure, they have auto-pilots, but they're not available wirelessly to anyone on the ground, and you certainly can't even use auto-pilot to land a plane. Although the pilot was a flight-geek, I think it's beyond unlikely that he retro-fitted any sort of automation system during the flight while the thing was in the air.