|Would a 9-11 type hijacking work today? No, because if someone jumped up with a knife and tried to hijack a plane, the passengers would swarm the bastard and beat him to a pulp. In fact the "shoe bomber" was detained that way.
Starting from day one we should teach aggressive defense techniques not passive-submissive responses to threats. If everyone in a lecture hall throws their books,backpacks,shoes,laptops,chairs,and desks at a threat, he will have a tough time with his marksmanship. He could then be swarmed and dispatched. This needs to be taught early and often. If the first class the Virginia Tech shooter attacked had responded this way he probably would have hit several people but not made it much further.
Teach response not submission.