If any of this is true, it seems a hopeful sign. The article has two helpful maps. One shows areas controlled by ISIS and others by some combination of "government and other rebels," which is an interesting way of having to put it. The other shows the origins of foreign supporters traveling to ISIS. Much of the article concerns tensions between locals and these new arrivals, some of whom don't particularly want to fight and all of whom, no matter how dreary a situation they left in their home countries, are accustomed to a higher standard of living than the locals. Many apparently are drawn by the idea of a culture in which rabid Islam is in the ascendancy, but had little notion what that might look like close up, especially if their clique isn't in charge.
I have slowly been reading "In the Shadow of the Sword," about the roots of Islam. I was skeptical of the author's thesis, that Islam developed in Syria, in a hotbed of conflict among Jewish and Christian sects over monotheism, and only later became associated with Mecca and Medina. But he makes a good case.
If ISIS did collapse, of course, it's not as though sane people would take over; Iran, more likely. Yesterday almost 50 Republican senators signed a letter helpfully explaining to Iran how treaties work in this country. Which Republican senators refused to sign? Lamar Alexander, Susan Collins, Bob Corker, Dan Coats, Jeff Flake, Lisa Murkowski, and Rob Portman.