If Boeing thought that this incident was similar in nature and they had no answers then the 777 fleet would be grounded ( a situation which very nearly occurred after the 2005 incident). The fact that Boeing have not issued any AD's to operators (to my knowledge) suggests that they are not concerned that the aircraft has an inherent fault that could cause another 777 to disappear. The crew in the 2005 incident were able to override the automatics and recover the aircraft. For something similar to have occurred there would have to be another undetected software failure followed by a double incapacitation. Something which IMHO would be an order of magnitude beyond 10-9.
I tend to agree with this, but I have to admit that my first thought upon learning of this incident was ADIRU failure and/or an EE bay fire. The latter still explains everything known about the incident except for one important issue -- how the plane wound up headed in the general direction of Perth and the supposed track around Indonesia (still not entirely convinced of that as established fact given the source).
As for Boeing, in the absence of evidence that there is a fault in the aircraft (and theories aren't evidence), there are ample economic and liability/legal reasons to do nothing unless/until concrete evidence of a fault is discovered. Grounding the 777 fleet would be an enormous hardship for a number of carriers for which this aircraft type is the backbone of their long-haul intercontinental fleets, a group that includes the three legacy US carriers.
You don't ground a fleet of aircraft in the absence of specific evidence of a design problem. Prior groundings such as the Comet I (c. 1952), Lockheed Electra (c. 1959), the DC-10 (1979) and 787 were based on physical evidence of a potentially catastrophic problem with the aircraft. In this case, such physical evidence is, to date, completely lacking.