In reading the staff report to the 9/11 commission, you find that most witness reports that they had were about slashing of the throats. Unless you had some sort of armoured outfit, I don't think you would be protected.
A bladed weapon is what a police officer fears. I went to the United States to meet with some officials there, and they said, “If you point a gun in my face, it's really easy for me to get that gun away from you. But a blade I don't see coming.”
I don't envision any of the airlines introducing that kind of protective clothing, particularly around the throat and other body parts. I don't think it would be effective, because even police officers with body armour can be slashed in the throat.
So I'll think about it, sir, but right off the top of my head, I don't think it will happen.