We heard this same rap when Saddam Hussein was captured.....
Unfortunately, I think he's right in a way. But remember that to subscribe to this line of thinking, you have to acknowledge that the death of Osama will not change things either -- which I think is more the case than al-Zarqawi.
I do expect some stepped-up and desperate-looking attacks for the next few weeks as the al Qaedites desperately try to keep the footsoldiers from getting depressed.