You two are giving the US far more credit than it deserves. I still feel that the second invasion of Iraq happened because George W. wanted to prove that he could do something his father couldn't, which was kill Saddam.
One does not exclude the other. Politics is always a combination of strategic goals, tactical constraints, and random idiosyncrasies of the leaders. And war is just another facet of politics.
Turkey is in for a hard dose of reality, I think. It is already becoming apparent that the Kurds are more valuable allies.
Never. America, with all its might, cannot afford to lose Turkey's support, it's a far too important ally in the global equation. What the US can do is convince the Turks to accept a Kurdish state at its border, maybe by offering them another kind of strategic advantage as a compensation (besides the guarantee of its own territorial integrity, which is already provided by the NATO treaty). That's not uncommon in international politics.
That sounds kind of insane.
Why so? If you think that politics is a flower-power festival where people hang around having a good time, think again.
Kurdish terrorist are no different from Irish terrorists or Spanish terrorists or Muslim terrorists.
Oh, but they are different. By the generic definition of the term, you're of course right, but there are always nuances that make all the difference. There could never be imagined a negotiation with the ISIS, no matter what, which was not the case with e.g. the Irish.