There will always be some Muslim fanatics that want to reestablish the Caliphate, because it is mentioned in the Koran, just as the End Time scenario with seven headed monsters, Armageddon and all that crap is mentioned in the Bible.
Defeating Isis is a job for the Sunni Muslims. All the US and other non Muslim countries can do is help. We have proven many times in Asia that we cannot turn Asian societies into anything we would like them to be: in Korea, Vietnam, Philippines and Iraq. It is akin to trying to create a perpetual motion machine: impossible. A am all for giving the enemies of Isis what we can to help them, but we have no business sending troops. If we could spare the men and the money it would be useless. The Muslim World is not yearning to become Southern California, though there are a few who think this is what they want.