Profiling and pax screening is neccessary, after all most potential hijackers will be of a middle eastern appearance. Quite easy to spot really. As for those who cry racism, tough. I'm Irish and like most Irish accompanied males not wearing a suit, I've been searched and questioned many times on UK /Ireland routes. Thanks to the activities of some of my less civilized countrymen. I don't mind too much. Other nationalities need to get used to the idea too and get over their highly developed sensitivities.
On another point I'm still wary of arming pilots with handguns. It might work but there are complications. One scenario is the overreaction to a drunken passenger. Shoot him dead and will manslaughter charges follow?
Then there's the conventional hijack scenario, 'take me to X', which is easily the most likely next situation. A gun battle with the pilots doesn't bear thinking about.
Personally though, I don't believe they can realistically duplicate that the 9/11 attack. It took a lot of training and money to get those b******s to the level where they could actually hit something. That would be hard to do again.
A secure cockpit door is really the best option, if they can't get in they can't take over.
I have to say though, I believe they have shot their bolt. I don't see how they can survive the the pressure on them now. There will be more terrorist attacks but not on the same scale. I think we'll see the sort of low level terrorism we have come to know and love in Europe for years but no more. The current treatment of Afghanistan is an object lesson for other countries in the area.