I have heard the idea before (did you write it somewhere on the .org ?)

Two problems i see with it mainly...

1) how bad would america have to be to unite iraqi's against it ? we have had the abu gahrib incident, gauntanamo bay, these are considered quite horrific acts by american standards and it has caused little in the way of unity, i think you need to be the kind of conquerer hitler and stalin were to thier provinces

2) would they even get behind one leader in the first place or would they just consider they're own struggle for independance, i can imagine the sunni's and the kurd's not really caring for shia freedom or lack of, they would probably just form 3 different local resistances...