Iran is terrified of Kurdish autonomy/statehood in northern Syria and northern Iraq because it knows very well that the emergence of a Kurdish polity in the region will inevitably undermine Iran's territorial integrity, in view of the fact that there are millions of Iranian Kurds and that a lot of them might be encouraged to demand greater autonomy or outright secession if they feel that the dream of an independent Kurdistan is on the verge of being realized/fulfilled.
Turkey undoubtedly shares Iran's fears and concerns due to its very own sizable Kurdish population, therefore it comes as little surprise that the Turks and Persians are willing to set aside their ideological differences over Syria (and even Iraq) for the sake of ensuring that the Kurds of the region do not succeed in establishing a political entity that might potentially redraw the borders of both Turkey and Iran.
Unfortunately for the Turks and Persians, time is actually on the side of the Kurds by virtue of their superior fertility rates. The Kurds are outbreeding both the Turks and Persians, and it is expected that half of Turkey's military-age population by 2050 will identify itself as Kurdish.
In any case, it will be very hard for Iran to glue Syria back together. The Americans and French have already established a long-term military presence in Syrian Kurdistan, otherwise known as Rojava, and there's no indication that they are going to leave that region anytime soon. For now at least, it appears that the Americans are still committed to the Syrian Kurds, albeit they might not give them the green light to capture the entirety of northern Syria. Additionally, the Russians also seem to be sympathetic towards the Syrian Kurds. In fact, it is the Russians who have proposed federalism to the Syrian government as a solution for ending the civil war and as a means to prevent the official breakup/fragmentation of the country. Ultimately, the Russians will have the final say on the issue since the survival of the Assad regime depends more on Moscow than it does on Tehran.
I'm afraid it's too late to roll back the territorial and political gains of the Syrian Kurds. Even Turkey has conceded that this is an impossibility, which is precisely why Erdogan is trying to convince Iraqi Kurdistan's Masoud Barzani to find a way to replace the YPG units in Syrian Kurdistan with Rojava Peshmerga forces instead. From Turkey's point of view, a Barzani-controlled Kurdish state (i.e. Kurdistan) in northern Iraq and northern Syria is tolerable and is a much better deal than a PKK-aligned Kurdish state.
Salih Muslim to a Saudi paper: Iran pushes the regime to block federalism in north Syria; Iran is a real barrier toward a solution in Syria.
The original paper article:
http://www.okaz.com.sa/article/1523587 (Arabic)
Turkey and Iran may have different opinions on the Syrian issue but I do really believe that both countries at least are respecting the territorial integrity of Syria. But sometimes I'm starting to believe that the main goal for Riyadh is simply to eliminate Assad without caring about the consequences. There is zero chance that a communist terrorist can talk to a Saudi paper without the explicit permission of Riyadh.
While it's true that Saudi Arabia is obsessed about the overthrow of Assad due to his close links with Iran, it must also be borne in mind that the vast majority of Gulf Arab states, especially Saudi Arabia and the United Arab Emirates, are extremely wary of Turkish and Iranian expansionism in the region. Consequently, countries such as Saudi Arabia and the UAE will become increasingly supportive of the Kurds over the coming years in order to use them as a counterweight against both Iran and Turkey. Israel will also become more pro-Kurdish in the coming years as well. Qatar is perhaps the only country in the GCC that does not hold these fears.
