I remain sceptical but there's also a fact we continue to deny to this day:
America had decided to support PKK just after our government failed to form the TFSA back in 2014.
Remember these news?
http://www.hurriyetdailynews.com/2000-syrian-rebels-to-be-trained-in-turkey-74353
Maybe - just maybe - the Americans has changed their opinion about our capability to bring those Sunni Arab masses under our control, after all FSA is still representing the majority of the Syrians even though they lost to SDF and Assad.
Another fact that people almost always forget: Kurds are a small minority in Syria and the vast majority of the SDF forces are consisting of Sunni Arabs. The numbers for the Kurdish population decreased drastically after the beginning of the Syrian war. At least 100.000 Syrian Kurds are living in Germany as refugees now, according to the German government! This is huge.