Seems tha the Bush family was very angry with Saddam Hussein and used they a bit influential position to move all the world in a war to solve that problem.
For this, they alleged that Iraq has a lot of mass destruction weapons ready to overtake the entire "free" world, that they will give the weapons to terrorists, that they eat children and they have all their population under slavery, so they must be stopped with a large scale war.
Now, after the UN inspectors, almost no weapons that could be calified as for mass destruction (more than weapons that could reach long distances) has been found, and the "dangerous" ones were destroyed, but even with this, the war started, against a almost unarmed country, risking the lives of several millons of peoples that "want" to be freed.
Now, what will happen if no mass destruction weapons are used by iraq (the alleged reason for the war) nor found (or is not clear if the ones that they possible find in an hipotetical future are planted by US forces), what if the alleged reason for the war proved or is in doubt that it was valid?
What changes in the world could this make? I suppose that the media could manage to give the world the impression that US was right, that this had to be done, showing only happy people in Iraq, showing fake or planted nuclear, chemical, biological or whatever weapons that the public opinion could want to see, but for the ones not impressed by the things that the media could show.
For a start, I could see an increased hostility to Bush in particular and US in general. If the wining of the war gives Bush popularity inside their country, then a reelection will be almost sure, and things will only grow worse. If US do this with impunity, they could do this again. As I said here, half joking, half talking seriusly, truth can be manipulated to justify the attack to more countries, north corea, pakistan, cuba, china, other non "democratic" countries, etc.
Once you say that you are doing war in the name of peace and attack before the other could attack you, you can do anything
In my country a newspaper on what I don't have a good opinion put in their front page "Hitler invades Irak". In World War II Hitler started invading countries saying that in the country there was nazis wanting to be freed, not so far from current situation (maybe we won't have mass killing of muslims, but, who knows, by now anything look possible). I know that this comparisions could make a lot of people angry, but saying "i'm not like that" and doing almost the same things not helps avoiding this kind of things.