I'm certain it can provide some degree of closure to at least some of the 9/11 families.
Insurgency is a crazy subject, especially combined with religious extremism. Do I think it will have an impact? Yes, although no where near as much as the little boy or the fat man had on WW2. Do I think it will change anything? Not really, the point of the war wasn't to kill Osama, so the troops certainly won't notice, hell I'm sure there are still tons of Al Qaeda who don't know about the death/ think the U.S. is FOS, even if they do, it won't take long for them to reorganize and continue as always, meanwhile the casualty list will continue to be filled. We're in this until it's done.