[jacquesm]

This is a very simplistic view of an airplane crash. The whole airplane is the crumple zone for the black boxes mounted in the tail of the aircraft, that's for a pretty good reason so there goes one assumption, it's not like they are in the nose. And for another, those black boxes that were lost usually were lost either because the whole airplane was lost or because of the post impact fire.

There are some instances of flight data recorders and cockpit voice recorders that were destroyed but not a whole lot of those. That said, this was an exceptionally violent impact and it remains to be seen if there is anything usable.

But - again - speculation is utterly pointless there is simply no information to go on other than the angle and speed of impact, which definitely isn't giving hope, but it doesn't rule anything out either. So let's just be patient until there is actual data. Nobody ever said that black boxes are indestructible.