No, they wouldn't. In the 70's the unwritten rule was: you hijack the plane, land it, make your demands, get your TV time, and then you surrender (or get away) but no one gets hurt. It is only because of that unwritten rule that you could get away with it because everyone assumed that the best route to survival was to cooperate with the hijacker.
All that changed on 9-11. Cooperating is no longer seen as a viable option, and so if you try to hijack a plane you can expect the passengers and crew to put up a fight. At best you can bring down the plane. But you won't get your TV time, which is what most hajackers really want.
Actually, you don't even need to look at the track record on airplanes. The TSA, by making everyone stand in line, is creating a nice soft target just outside the security zone. Any terrorist who wanted to make the headlines would set off a bomb in the TSA line at O'Hare. It would be trivial. The fact that no one has tried it is more evidence that our fear of terrorism is a vastly bigger problem than actual terrorism.