No one will survive an attempt to hijack an American flag air carrier for at least a generation.
Mortal lock that at least one in four people on the plane will immediately go into "let's roll" mode as soon as the hijackers start (based on my friends and co-workers, both men AND women, that 1 in 4 is REALLY low-ball). Beyond that, no one is getting through the doors into the cockpit. Even if they somehow figure out a way to try, the air crew is almost certainly strapped and will blow their ass to Mars as soon as they crack the door (assuming there isn't an air marshal on board who rings them up first).
This isn't to say that someone might not TRY to hijack a plane, just that they will fail to gain control of it. They might blow it up, that probably will happen at some point, but actually gain control?
Flat not going to happen.