I'm leaning more bomb than either sabotage or cat. engine failure.
It's starting to sound to me like a re-run of the Concorde accident: tire picks up runway debris and hurls it into the wing, fracturing it and starting a fuel leak... fire ensues... piece of wing shears off and takes out the tail, per witness. End of airplane.
I have no ability to authoritatively comment on your hypothesis that a piece of debris killed 261 people. It would just seem to me as a layman that the Concorde would be much more sensitive than an Airbus. Unless the French/Europeans are simply totally incompetent in their structural design.
It's starting to sound to me like a re-run of the Concorde accident: tire picks up runway debris and hurls it into the wing, fracturing it and starting a fuel leak... fire ensues... piece of wing shears off and takes out the tail, per witness. End of airplane.