My concern is, will the USA stick with them after our goals are met? We have had a bad habit of abandoning people in the past, and Turkey is eager to expand into this area. Rojava is already a defacto state, and Syria will accept that with pressure from USA and Russia. What will be offered to appease Turkey?
The McCain wing of the GOPe, the State Dept and the Saudis still love their Jihadis in the FSA, even though they would stab us in the back at their first opportunity (and would probably be worse than Assad). They will try to block or minimize an SDF/Kurd victory, as that marginalizes the FSA and preserves the Assad regime.
Turkey is not going to be appeased. They would exterminate the Kurds just like they did the Armenians.
We have already had to block the Turks with our military, it is a very dicey situation. We are in agreement with the Russians to support the Kurds.
We need the Kurds as a stabilizing Islamic force.