Not necessarily. It depends upon whether there are real dividends to peaceful coexistence or whether returning to religiously sanctioned theft is more profitable.
As I understand it, Iraqi Sunnis consider themselves to be vastly superior to Iraqi Shiites and Kurds. A permanent American force is required to make the Sunnis to serve under the American-installed Shiite-Kurd government. If American power ever recedes, Sunnis will seek to regain the domination of Iraq they previously had under Saddam.