Yes, of course they will, but the PKK is also an old enemy of Peshmerga. This is an enemy-of-my-enemy situation, and I don't think either side there still likes each other. It is just that ISIS is worse.
Wait. Is the PKK allied with the Peshmerga?
UK and USSR and USA in 1941.Finland and Germany in 1941.
In fact, you could say these guys weren't officially ISIS militants. They were heavily inspired by the terrorist groups, but not directly involved in the ISIS/Al Qaeda shell.
"The terrorist threat was not created by the Iraq war 10 years ago. it existed even before the horrific attacks on 9/11, themselves some time before the war.
"This threat cannot be solved simply by dealing with perceived grievances over Western foreign policy. Nor can it be dealt with by addressing poverty, dictatorship or instability in the region - as important as these things are.
"The root cause of this threat to our security is quite clear. It is a poisonous ideology of Islamist extremism that is condemned by all faiths and faith leaders."