There are a lot of people in the U.S. who share your gloomy outlook.
I'm glad to say I'm not one of them -- I think the people of Iraq will be happy to be liberated. Muslims in other countries will likely grumble about our actions, but on the other hand everybody admires a winner. And when they see the people of Iraq aren't badly treated I think the overall reaction will be muted.
We're soon going to see if you're right -- it won't take long after the war begins to see how the population of Iraq (and the rest of the region) react to Saddam's overthrow.