The American military have said they believe an Egyptian militant, Abu al-Masari, is likely to take over as head of al-Qaeda in Iraq following the death of Abu Musab al-Zarqawi.
Many supporters of the insurgency disliked Zarqawi's brutal methods
And there have been warnings that Zarqawi's death is not likely to lead to an early end to the insurgency.
A senior American general said that sources within Zarqawi's network gave intelligence that helped the Americans and Iraqis to track him down.
That fits with a number of recent assessments, indicating that Zarqawi was losing popularity, even among his own supporters.
There has been a vigorous debate on insurgent websites in recent months about Zarqawi's brutal methods, particularly his gruesome trademark of videotaped beheadings.
Several sources close to the insurgency had suggested in the last few weeks that Zarqawi's role had already been downgraded. He was also criticised recently by Osama bin Laden's deputy Ayman al-Zawahiri.
Zarqawi's tactics fuelled sectarian divisions
Many supporters of the insurgency feared Zarqawi's brutal methods were discrediting their cause.
But there was also disquiet over his vicious hatred of Shia Muslims (Zarqawi himself was a member of a radical Sunni Muslim sect).
Zarqawi's group was blamed for many of the worst attacks on civilians, both inside Iraq and in neighbouring Jordan.
So Zarqawi's death provides opportunities, both for the Iraqi authorities and for the insurgents.
Clearly it will be a boost for the new Iraqi government of Nouri Maliki.
The new prime minister will hope he can begin to steer his country away from the danger of a sectarian civil war between Shia and Sunni Muslims.
He has also demonstrated his credibility, as someone who is tough on security.
New unity for insurgents?
But the insurgents might also use this as a chance to refocus their campaign, perhaps concentrating their fire on the security forces, and away from the attacks on civilians that Zarqawi pursued so cynically.
That in turn could help the fractured insurgency to work together more effectively, and might also help them win more support from the Iraqi people.
Iraqis will remember the brief surge of optimism that followed the capture of Saddam Hussein in 2003. They will be fearing this may be another similar false dawn.