I favour the US & any other foreign nation staying out of Iraq and let the locals sort it out themselves. The way I see it any foreign interventions, especially US and / or NATO and / or US led Coalition is just going to exacerbate an already bad situation in that it will inflame the situation and prevent any long-term eventual solution to the problem. The only practicallong term ssolution I see is that Iraq as we know it will disappear into the dust of history and two possibly three nation states will replace it.Iraq, as we have known it, is probably gone now. ISIL appears to have expanded the Syrian battlespace into Iraq in a contiguous way. A couple of observations then. It seems unlikely that ISIL will be "defeated" directly in the Syria-Iraq sphere anytime soon without significant US military involvement. However, it might be more useful to just contain it. If the US directly attacks ISIL in Iraq (air strikes, SpecOps, etc) will it not be pressured to extend those efforts into Syria as well? (Not to help sad --- ISIL is fighting against most of the other rebels too, it seems.)
But might the US encourage Turkey to work with the Kurds who have seized the oil facilities in the north from ISIL, plus encourage what remains of the Shiite security forces and governance in the south, to just lock up ISIL where they are now? Perhaps after a while the landlocked and isolated ISIL fighters will begin to feed on themselves.
I think Turkey needs to accept that it has to change it's policy regarding the Kurds and that a Kurdistan with contiguous borders is now quite a probability. Speaking of which, the TV news here has shown some clips of the Kurdish Army in action and I was quite impressed with their discipline, especially their fire discipline. They looked like a professional army.