I don't think you could say that this crew of AF447 , were ever in danger of performing a near optimal manoeuvre.
The sim tests in a 320 mentioned earlier give 18000 as an achievable figure, my fudge factor of 50% I think would be reasonable netting a cool 27000!!
So somewhere between 11000 to 27000, I can guarantee you these numbers would be known by very very few line drivers(or senior management )
Is it naive to suggest that those who wanted to live out their careers would find a way to learn it?
Or at least how to follow the unreliable airspeed checklist when they had unreliable airspeed?