The Atlantic magazine published an excellent piece on the ISIS explaining what they really want.
I don't think the majority of people read this magazine. It would be really troublesome if they do. Many readers are going to go away thinking ISIS is really a version of Islam. It isn't.
What ISIS wants is to bring on the apocalypse as foretold in the Quran. Given time it will get the first half of its wish but I doubt the second half will materialize. In that first part, they will get destroyed and end of story till another try. Pretty much like Christian cults waiting for the end of the world which never came.
With ISIS destroyed militarily and territories reconquered their caliphate will temporarily come to an end.
The problem though would not go away until Salafists are given opportunities to practice their beliefs, and in my view be disillusioned by them. There is no learning this except by the hard way.
Even if Baghdadi is killed they will find another Qureshi eventually to take his place. Then if ever we are careless, fight the next generation of ISIS all over again. They will keep trying to bring on the End of Days until enough Muslims get fed up with it because it is not happening and give up supporting them. This will pave the way for a more patient and co-existing with others Islam. The written word of their faith wouldn't have changed of course, but they will be understood differently.
Their holy writings describe a military Armageddon with Muslims as protagonists. This is the opposite of Revelation in the Bible which the Christians/Jews will be hunted and killed. Some crazies will always entertain "forcing God's hands" by initiating the sequence of events leading to the End of the World.
Global events must flow in such a way that some of these believers do not read them as signs of the coming of the End or else this problem of Muslim related terrorism will keep reigniting. How Israel currently conduct itself in that region is a real problem too. World leaders must understand Islamic prophecies and act to create a different environment which these religion terrorists cannot find the tea leaves they seek auguring the End of the World.
And what if we fail? This problem will get worse and if the terrorists have more stamina than the rest of us they will keep at it until it is really the End. A very bloody end quite like their book.
Update: Feb 23 10:55 am
There will be more of such. The quiescent Muslim majority are self organizing and responding because tipping point of watching and not doing much is over. Similarly non-Muslims will also come together to protect their minority Muslims as appropriate.
No reason to be pessimistic. End of the World? That's not our business. Don't interfere with the Divine. Have some respect, even fear for him.
Don't want "The World to End?" Then don't act to produce those signs so that none of the apocalyptic faiths would cue from them and act stupidly.