It seems like ages ago now but early on it was speculated that a crack in the fuselage could explain both decompression and loss of communication. Something in the dark recesses of my mind tells that this theory was dismissed as not applying to the 777-200er though. I could be wrong and it may be worth investigating again.
http://m.smh.com.au/world/missing-m...warnings-over-boeing-777s-20140312-hvhqz.html
The US airline safety regulator warned last year of cracking in the fuselage skin underneath a Boeing 777s satellite antenna, issuing a worldwide alert for the flaw to be fixed as it could lead to decompression that would leave occupants unconscious.
A structural failure related to the flaw could not only have led to a slow decompression that left the 239 passengers and crew on the missing flight unconscious, it would also have disabled satellite communications, including the Aircraft Communications Addressing and Reporting System (ACARS), which transmits data of the planes location automatically.
It would also have rendered the plane invisible to all but 'primary radar', which has a range of only 100 nautical miles.