You have to differentiate between the Syria’s western and eastern Kurds. The former are too distant from the Kurd heartland and their territory has no contiguity with Kurdistan. Eastern Syria, Al Hasakah, (and perhaps portions of other eastern provinces),,is a sure bet to join Kurdistan if allowed.
I Don’t see a real obstacle. Even the Alevi around Efrin totally support unity in Rojava. With KRG? Totally different question. Secularism is a must in all of Northern Syria.