The only wildcard on all of this is what Turkey will tolerate if and when the Iraqi Kurds decide to declare an independent Kurdistan. Turkey shares a border with Iraqi Kurdish territory, and has a large number of ethnic Kurds who would love to take the land they live on in Turkey and join an independent Kurdistan.
This is yet another potential tripwire in all of this that has the potential to light off an even larger territorial conflict that is growing to include most of what used to be the old Ottoman Empire. God help us all if anyone in that vast group of conflicting interests ever decides to introduce a nuclear weapon. We already have widespread use of chemical weapons of mass destruction in Syria that has gone largely unchallenged except for the Russian engineered sideshow of removing some portion of Syria's outdated chemical precursors. The Syrian Army has switched over to using chlorine gas instead (which is easily produced to use for water purification) and eventually they will step up the pace once again.
The three-state solution is also known as the "Biden Doctrine" and dates back to when Joe Biden was on the Senate Foreign Relations committee and constantly harped on this dangerous solution as far back as the first Gulf War. What you see going on now in Iraq is exactly why the US did not pursue this path, and in fact worked for years to prevent exactly what we are seeing today.