Now that it's war, of a kind - civilians indistinguishable from 'military' - the "are guns good?" arguments rendered moot, for the foreseeable:
Blackjacks issued to all passengers who want one (no revealing who has one; issued behind 'screens'). Not nearly so fraught with implications as any projectile weapon. Ineffective against thugs armed with those, though an opening could occur - certainly better than bare hands against sharp weapons. Good use for a handheld, laptop too.. via leather carry straps.
It seems that - any future hijacker will need guns and.. if outnumbered 10:1 - only human performance each event, can determine next outcome.
I'm sure there are dozens of *good* ideas, among the thousands - which could next tip the odds, and without massive airframe alterations. (Fly nekkid under paper disposables, for one).
Time for that vaunted Yankee ingenuity !!
A.