Assad can't control all of Syria. He has effectively abandoned all but isolated outposts outside of the western region from Aleppo to Dara that he is fighting for.
Syria's Kurdish region is out of Assad's control:
Syria’s approximately 1.7 million Kurds, nearly 10 percent of the population, are the only group with a history of organized opposition to President Bashar al-Assad’s government, but while many towns have seen anti-government protests during the 18-month uprising, they have refrained from joining the armed opposition.
As the uprising has evolved, however, the Kurds — largely concentrated in the country’s northeast, which holds a significant portion of Syria’s limited but vital oil reserves — have been quietly preparing for a post-Assad future, opening police stations, courts and local councils that they hope will form the foundations of an autonomous region. ...
But the effort to achieve self-governance is taking place while the government’s troops maintain a presence in many of the region’s towns and cities, appearing to turn a blind eye to what would have previously been an unthinkable threat to its power.
Assad can stick it to the Turks by doing nothing. Kurdish activity stands as a reminder of blowback should Assad's regime crumble.
Which is why I'd expect that if NATO goes into Syria to either control chemical weapons or for humanitarian reasons, Turkey will have their own mission in the northeast to suppress the Kurds.
I also have to wonder if the Kurds have made a deal with Assad that allows the Kurds to hedge their bets. Is Assad making the best of the situation by promising more autonomy for the Kurds if Assad wins in exchange for the Kurds not piling on?
This makes sense for Syria's Kurds who have reason to fear the Turks if the Kurds pursue more right now--even ostensibly on the same side against Assad--and who can hope for perhaps more if Assad loses the revolution.
Of course, the Syrian Kurds are divided, too, adding more conflicting interests.
