This talk of ADIRS failure is pure nonsense - simply doesn't explain the situation.
With the available info (admittedly quite sparse), I can't get passed the idea of a catastrophic structural failure. What I wouldn't like to speculate on is the cause, except to note that in 20 years of 777 operation, nothing like this has even come close to happening (compared with the likes of the 747 and DC10 where there were several structure-related occurrences).