Bloody hell this is grim stuff, not helped by some of the insensitive crap on this board by some. Sadly though, it looks more and more like an electrical storm has taken this and the poor souls on it down.
It's not that long since the similarly mysterious Kenya Air crash in Cameroon which IIRC is suspected to be storm related albeit a bit closer to take off than this one. Given the 330's near perfect safety record to now, it is hard to think of an uninduced fault mechanically being responsible for taking it down.
Those equatorial storms are horrible and i hate flying down to JNB with those things around as it gets very bumpy at times - incidents like this just make you wonder if sometimes we just get a bit too close to them. Who knows the truth though. Sympathies to all affected.