Yes, the demographics in Iraq would allow for clear partition. The Kurds are mostly in their own region, and their government is largely separate. This is not to say that partitioning is wise or needed, but if it did happen, demographics and rational lines in Iraq are quite separate and a partition could happen if managed properly without significant upset.
While anybody with a clear knowledge of the Middle East could understand the regions predominantly Sunni/Shiite/Kurdish, by this point in history, redrawing the borders would only turn internal conflicts into wars. Many countries throughout the world have ethnically and religiously diverse populations without serious threats of violence, and portioning a country seems infeasible right now.