Well as much as it is against my religion, I hesitantly agree with Pete on this, there seem to be too many other variables at play here for the Goodfellow theory to be as close to actuality as some think. My immediate question, and this assumes that the current 'crash zone' is of course accurate, is how can an electrical fire of any sort, that managed to disable almost all communications [apart from the satellite pings] and over come the pilots, not take out anything that George needed to keep it flying until it finally ditched 7 hours later? Secondly, what were the cabin crew doing during this time? Even if the passengers didn't notice anything wrong, the cabin crew normally have communications with the cockpit, even if it's only to offer refreshments [although possibly the cockpit crew have their own supply ref security?], and I can't believe experienced crew would not detect there was something amiss, surely such a fire could not have been so comprehensive as to take out the entire crew and passengers all at once whilst still being able continue to fly?
Having said all that, I am not yet prepared to dismiss such a theory totally out of hand either, I just think a lot of questions would need to be answered to verify it. None of which can even begin to happen until flight recorders and wreckage are retrieved - if indeed they are. This could remains a mystery for many years.