Yeah, and that's only the beginning of the problem. Then comes the practical one - who gets resettled to where, and how do we get the "where" to agree and provide passable housing, public services and sooner rather than later, job market there for all the resettled people.
And then there is the fact that knowing the region and populations involved, there will be a bunch of insurgencies (or worse, hybrid wars), possibly long lasting ones, acting on their respective group's unhappiness with the abovementioned details, while the whole idea is to give USA less peacekeeping work in the region, not more.
And last but not least, it kind of ties into the military and population happiness issues, it's no secret that there is a disturbing amount of amateurs of red color among influential Kurdish organisations, and they would most likely become major power players in the Kurdish state's politics. That does not bode well for it's economic prosperity, and in turn, military capabilities. Sure, they may have half decent organisation and loyal troops, but that only goes so far without money, so they won't be Israel 2.0, certainly not within foreseeable future.
Arab or not, i seriously doubt they are even remotely interested in being ruled by Assad and/or paying for Syria's post war reconstruction and general "uplifting" of the bulk of Syria that was relatively poor even before the war. Even if the issue of the former is settled, the second one may get even worse in the process. I don't really have a dispute with your qualifications about a Kurdish state, just the observation that it wouldn't be any worse than the far more futile effort we've put into Iraq.
