Excellent post. I learned a lot from reading that - you definitely know more about the history of that country & the current dynamics than most.
In regards to the Kurds, I don't think the US will go out of their way to establish a formal Kurdish state. The west has abandoned the Kurds time & time again, I don't think this time will be any different...
Turkey is a crucial ally in that region (albeit a super sketchy one)
If Turkey is opposed to the SDF, they'll play extremely dirty to help persuade western governments from supporting the Kurds to the point of finally establishing their own state.
"Hey Europe, want another million refugees by this time next week? Oh you don't? Okay, well, better stop assisting the Kurds to establish their own country then...yeah?"
I imagine the general synopsis of that convo might be along the lines of the above...