Turkey, the US and the Kurdish people have differing goals in Syria, with the US trying to recruit the Kurds against ISIL and the Turks trying to recruit the US against the Kurds.
In the middle of all this is also an odd (alleged) attempt by Israel to develop some kind of treacherous alliance with the Kurdish people against Iran (a longtime friend of the Kurdish people). If true, this would itself clash with both the interests of the US and Turkey in Iraq and Syria and make the situation even more complicated.
While many countries including the US claim to have recruited the Kurdish people for their own agenda, the main priority of the Kurdish fighters has consistently been to defend their historic homeland in parts of Syria, Iraq and Turkey. While anti-Assad fighters in Syria claim that the Kurds will help them remove Assad from power, so far the Kurds have shown no deviation from their original goal of defending their homeland from anyone who tries to interfere with their national goals.