Well Kurds need their own country. Iraq as we know it should be split in 3 pieces because it won't settle down until then. Like many of the middle eastern countries it's an unnatural Frakenstein creation of 20th century European imperialism anyway so not much to lose
We all know that. Try telling our NATO ally Turkey. Or Israel in regard to Iran swallowing up or controlling southern Iraq. For that matter our masters, Saudi Arabia, would not be happy with that at all. And unless ISIS is wiped out in the middle, they'll just continue to fester there because neither the Kurds nor Iran will want to be occupiers of that mess.
At this stage in the ongoing disaster it would probably be easier to build a time machine and send someone back to 2002 to convince Dumbya to leave Saddam Hussein alone than it will be to fix the mess by drawing new tribal borders over two failed states in Iraq and Syria.