Realistic outlook
Iraq does not have a guarantee of becoming a successful democracy. It has a good chance at it, where it had zero chance before, and that's at least something.
In my opinion, Iraq's real struggle is going to be against corruption in their own government and security forces. The corruption that is part and parcel of any totalitarian system is not easy to peel loose from, as was seen in Russia.
There will be ethnic issues as well, but not as serious IMO as the corruption.
If they can deal with that, and get a few successful elections under their belt, then terrorism will be no more of a threat to their continued existence as a democracy than it is for Israel. Or Britain.