There are two possible schools of thought on the importance al-Zarqawi represents for the Iraqi rebellion.
One is that he is a vital commander and strategist without whom the rebellion would flounder and fall apart. As Robert A. Norton writes in AG-Security.com, “Capturing al-Zarqawi, or more likely killing him, will have a profoundly positive effect on the morale of both U.S. and Iraqi forces and take a great deal of the wind out of the sails of the insurgency. If nothing else, it will prove that al-Zarqawi isn’t invincible and therefore must not have been protected by Allah, an important psychological element.”
The other school of thought is that while al-Zarqawi plays a leading role in his group's ideological and financial structure, the group can, and likely will, continue to function without him.
A recently updated organizational chart of al-Zarqawi’s group, posted on the website http://www.globalterroralert.com/pdf/0505/zarqawichart.pdf, provides insight into the operational structure of Tanzim Qa'idat Al-Jihad fi Bilad Al-Rafidayn. The commander of the military wing of the organization, Abu Usaid al-Iraqi, is still listed as a fugitive, as is Abu Abd al-Rahman al-Iraqi, the organization's deputy commander. The three main military leaders of fighting brigades are also free.
This would suggest that al-Zarqawi leaves the day-to-day planning of terrorist activities to commanders and cell leaders, rather than playing a direct role in insurgent activities.
How his possible permanent or temporary removal from action could impact on the group’s fighting ability is therefore problematic and premature to predict, but given the organization's structure, it is likely to function very well, at least in the short term, without him. The group's ability to function in the long-term would depend upon the ability of his successors to carry out recruitment and fundraising activities. Should al-Zarqawi die, Iraqis should expect a wave of terrorist attacks carried out in his honor, with insurgents declaring him a martyr.