Iraq is a country that should never have been. It was never formed from any typical commonalities such as language, culture, religion, and/or political beliefs. Nor, was it formed by any alliance for trade or security purposes.
Instead, is was created by a mandate of the League of Nations in 1920 which gave Britain control of that area in what was to be called the State of Iraq and what we know today as, simply, Iraq. Completely ignored in that process was how secular the country was with two primary factions of Islam at odds with each other: the Shiites and the Sunnis. At the same time, that "League" mandate completely ignored the fact that the Kurds of northern Iraq -- although Sunnis by religion -- had no language or culture that was even close to being in common with the rest of the country.
So, in essence, Iraq was, at the very least, three countries in one; only held together all these years by a variety of ruling entities and never by any self rule.
Yet, the U.S. government -- after invading Iraq and toppling Saddam Hussein -- foolishly thought it could turn this country into a self-ruled and cohesive state that could be governed fairly by a parliamentary style of government. But, the weakness of any parliamentary government is that, when there is an extremely dominant "ruling party" in charge, the minority party has little or no voice. So is the case in Iraq. What should have been done was to form had a power sharing triumvirate with the Shiites, Kurds, and Sunnis all having an equal say in control. But, that's hindsight.
The Shiites -- which make up 65% of the country -- have pretty much taken over through the elections of major chunks of the Parliament and by the election of "their" President, Nouri al-Maliki. Maliki, has, in turn, and where ever possible, replaced Sunnis with Shiites in government positions and in leadership roles within the military and police force. Thus you have a formula for revolt and/or all-out civil war.
What we are seeing right now with the incessant march of radical Sunnis -- known as ISIS or the Islamic State of Iraq and Syria --- down through the Sunni-controlled northern center of the country and on their way to Baghdad was inevitable. Already, the northeastern Kurdish territory has been cutoff from Baghdad and ISIS has established control in almost all of the Sunni cities in northern Iraq. Whether ISIS can overrun and overtake Baghdad in the same way that cities were taken in the north is anyone's guess. But, make no mistake about it, new boundaries are being drawn and those boundaries will almost inevitably become borders of new countries and no one can stop it from happening.
Obama won't stop it because he won't allow any U.S. boots on the ground. Whether he authorizes airstrikes and whether or not those strikes can be effective remains to be seen and, the Iraqi army is too incompetent and has little heart to stop it either. So, in the end, Iraq will probably become the three countries it was always meant to be, and Iraq, in less than 100 years since 1920, will be no more.