While I have to agree with some of the points Cedarjet, I don't think I could go quite as far as to say it could never happen on a 777. However, I do agree with the view that the reverser deployment wouldn't take the engine off the wing. I don't know about the second takeoff, but I think we'd have known by now.
Again, we come back to the Lauda incident. There seems to be a general view around that just because the facts don't fit EXACTLY, it couldn't have been the reverser. I still believe the reverser had to have something to do with it - nothing to do with the fact that it was No.282 or even that it had PW engines (which is a relevant point, however). It simply that the general course of events is quite similar to the Lauda crash :-
1) Failure to react on time, the aircraft drops suddenly and descents very steeply. The descent rates of the two aircraft are not far apart
2) breakup around or soon after the rapid descent. The Lauda aircraft lost its stabiliser and tail and it those "nosed over", fuel tanks ruptured due to stress and it blew up. MS 990 seems to have climbed, but this climb didn't last long, probably because the plane was overstressed; it broke up and went down. Different behaviours, but again most likely down to different reactions.
At this stage we are down to the question of, what else could have caused such a dramatic descent, but without robbing the crew completely of control, causing an overstress situation and a breakup. We can, I think rule out sabotage and a rapid loss of cabin pressure, but no doubt the CVR will provide the best evidence.