I'll stick with my contention that ISIS is not a function of some massive new scary threat, merely that of the power vacuum in the Middle East in this area. The Kurds are still holding their own. As is anyone capable of organizing and fighting.
Turkey would kick their ass, Iran would kick their ass. Jordan would kick their ass. Saudi Arabia would kick their ass. Egypt would kick their ass.
Israel would kick their ass, then grind the remaining ass chunks to dust, use the dust to make some sort of solid concrete out of them so they could then blow it up again.
The U.S. would vaporize them (non nuclear) and make the Iraq War I "highway of death" look like a minor skirmish. Except that we'd be hamstrung by some sort of crappy ROE.