Yes, historical examples show that partitioning can work, for example the break up of the USSR. The satellite countries are doing fine. Also the conflict in Bosnia resulted in a partition. That is working out well with strong leadership. Partitioning allows each ethnic group to have their own self-determination. It makes them more content.
After World War II, Germany was partitioned into four sections by the Allies. Only the part occupied by the Soviet Union failed to progress (East Germany), while West Germany (occupied by Britain, France, and the US), recovered far more quickly. Korea was also partitioned, and South Korea has prospered. North Korea, occupied by communists, has not. Based on these historical pretexts, at least a part of Iraq should also prosper if it is partitioned. This is better than the whole country failing as it is wont to do otherwise.