Actually, it's not just wishful thinking. The terrorists' real weapon on 9/11 was the attitude of acquiescence toward criminals in general, hijackers in particular, which was included in flight crew training and the public conciousness. That weapon is now gone, and it will be at least a decade before terrorists get it back, if they ever do.
Another knife-fighting expert . . .
For that matter, the passenger line of defense could be bolstered at trivial cost by putting a nice solid blackjack in each seat-back pocket.