To answer my own question, No. If killing Uday and Qusay, and capturing Saddam, both only proved to be bumps in the road to chaos, why should this be any different?
The main thing going on right now in Iraq is Sunnis and Shi’ites killing each other by the dozens. Zarqawi’s death isn’t going to make Sunni and Shia all lovey-dovey. There’s a low-to-mid-level civil war going on that had nothing to do with Zarqawi, and unfortunately it’s just as likely to keep on gathering steam without him as with him.
IMHO, his role has long been magnified by all parties in the war. The US’ motivation has been to identify Iraq as part of the GWoT. The Shi’ites in the government want to (a) go along with their American patrons, and (b) not be overtly anti-Sunni, because we wouldn’t like that. And the Sunnis want someone to point to and say, “Hey, it isn’t us that’s doing this.”
The one bleak hope I have is that, once the removal of the Zarqawi red herring has proved to make no difference, his absence might force the warring parties to acknowledge the true nature of the Iraq conflict, and address it head on. It’s not the way to bet, but at least it’s a hope.