They will always be on their side as long as the project looks feasible. The only way you can break that link is to do enough damage in syria and iraq that the pkk is no longer feasible and the americans won't waste their time and drop their support. But if you sit back and allow that bond to grow and grow, you will be facing a direct war with the USA in the future.
Think how bad things are now concerning syria, just imagine how much worse they would be today had Turkey not made pervious interventions. Every intervention makes Turkey safer and every intervention makes their hands weaker against us. Hence why they threaten us not to move, the threats prove if anything you have to move i sooner rather then later.
the project is feasible, because following
1. Israel's one of main problem is Iran . There for direction is toward iran, I mean path Syria and Iraq must be ready to be used as direction for offense. Therefor from 1990 to present usa main goal is to have this territory controlled.
2. usa do not want Turkiye to be independent and also do not want Turkiye to have control on Syria and Iraq territory which can potentially jeopardize prio 1 above.
all of this years since 1990 usa did not want to Show it intention. There for usa used all it is power to make pkk do the job for both main goals.
So there is no thing as feasible logic here. It is only one goal exterminate iran as thread for israel and second do not allow Turkiye to become independent and strong