I'm slightly changing my mind as to what happened. Or, at least now believe that there was a catastrophic fire (not mechanical) on board the aircraft that lead to the pilots disabling all electrical systems, eventual disabling of all the pilots/passengers and the plane just flew on autopilot and eventually crashed in the Indian Ocean when it ran out of fuel.

Pilots probably reacted accordingly, but simply ran out of time and options. They all died after the plane was put in an autopilot state, either by the smoke, or the eventual impact with the ocean.

http://www.wired.com/autopia/2014/03/mh370-electrical-fire/

Everything that happened so far reflects this theory.

Sadly, if you watch enough of the airplane accident type shows where they go over this type of stuff, this is probably the most legit theory out there.