I question to what extent there is an Al Qaeda as portrayed by the USA and whether there is too much misplaced focus on this "enemy".
The US seems to be promoting the idea of a Smersh type organisation with a central leadership controlling cells around the world. You cut off the head and the snake dies. Really the problem is fundamental Islamic militancy. So the enemy is more of a concept than a single group. It's like the mafia, if you capture the Don of a New York family have you eradicated organised crime throughout the world? I suspect that, aside from 911, Bin Ladins importance was that he had money and experience. So if you had a scheme you could go to him and if he supported the plan you could get financing for it.