I've followed this thread from day one, initially I was of the opinion that it was a similar scenario to AF447 ie tech problem that overcame the pilots.
At this stage it would seem to me that the most likely scenario is that based on the assumption that the Inmarsat arcs are valid, this aircraft was flown to its final destination in the sea by someone.
The fire theory doesn't stack up, if it incapacitated the pilots so quickly it would most likely brought the aircraft down sooner than several hours later.
The location of the current search focus and the route that would have to have been flown to get there more or less undetected back up my
theory that someone was flying this machine.
Can anyone explain how it could have gone where it 'seems' to have gone otherwise?
A truly awful event whatever the reasons