Nowadays, with secure cockpit doors and all the procedures, the possibilty of another 9/11 is almost zero.
Before, it was "fly to Cuba", then hostages and then 9/11.
Next time it will be something totally different. Not IF, but WHEN. But they will not use methods that we have prepared for. They are not as stupid as some think.
They seem to have won. They make terror and make our lives miserable.