The following thoughts may be over-optimistic and unrealistic, but here goes.
Up till now hijackers have been assumed to be relatively benign. Pilots have been told to cooperate with them (am I right about this?) and people have expected to just be inconvenienced by going to some other airport.
That will never happen again after this. So passengers and crew will be prepared to take risks to overcome hijackers. And surely a plane load of people can overcome a few with knives, if they're desperate enough.
Hijackers will realise this, so it won't be worth trying. Hijacking won't be easy, as it has been up till now.
So, could this spell the end of hijacking?
Like I said, probably unrealistic, but makes sense to me all the same.