9_11 worked because through either skill and good planning or totally dumb luck. The hijackers understood the systems in place and worked to exploit it. I've always thought the brains behind this never spent too much time in a cave in Afganistan.
The real problem is armed pilots is a response to the last attack. The fortified and locked door means rushing the cockpit is out. The passenger response will not be cooperative the next time. The hikackers know they need to neutralize/circumvent a sky marshal and or an armed pilot and control the pax.
So our attackers will be , probably are, looking at a plan B. Looking at the above it seems the obvious target is a freighter.
They may be evil
but they are not entirely stupid.
20driver