Well, they could have taken the little indestructible plastic cards in hand and brandished them when they charged the box-cutters.
Even though you are joking, in principle this would have worked. Or, even if they had just all taken off their shoes and thrown them at the terrorists in unison.
The problem is that the terrorists were claiming that they had a bomb, and that the passengers would be safe if they just complied.
I don't know how you pass a law against Claiming To Have A Bomb On An Airplane. I mean, you can *do* it, but a terrorist has already demonstrated willingness to break laws, so it doesn't accomplish anything.
Which is precisely why I can't stand all these suggestions being bandied about, trying to fix precisely the wrong problems. The problem was not that the people on that plane had no ID cards - that wouldn't have stopped it. The problem was not that the terrorists were able to bring razor blades onto a plane - it was perfectly legal and even if it weren't, they could have done what they did with Farber ball point pens. (We gonna ban those too?)
I can think of some real problems which ought to be addressed: Such as (1) that they were let into the country in the first place, (2) some of them were given taxpayer money to study their plane-flying skills, (3) some of them had expired visas but weren't deported, (4) some of them were known by the FBI to have terrorist links but weren't deported, and (5) there is a doorway rather than a strong bulkhead between the passengers and cockpit of these airplanes.
It is things like 1 through 5 which ought to be addressed and fixed. National ID cards will not help doing this one iota.
The whole thing is like amputating an arm because someone has heart disease. It makes no sense, doesn't address the problem, and makes you wonder why they are doing it.