What will happen is the nationalists will take over and eventually, create a better Iraq. There will be tremendous reprocussions for the US because what we did was insane. The world is looking elsewhere for leadership and we've not only empowered Iran beyond their wildest dreams, we've also made the EU, China, and even Russia more influential.
Even the reason why we started this war, oil, will get further from western control. The Iraqis know this war is ending and they probably feel no compulsion to sign the "let me rape your country" Iraq Oil Law.
I expect Maliki and much of his puppet government will be taking up residence in South Beach.