I guess you forgot al Baghdadi had declared himself Caliph, that's how you get to a Caliphate Jeralyn.  Without a Caliph do you have a Caliphate?

ISIS commanders have reportedly been executing other members and fighters since last winter in fits of paranoia.  If al Baghdadi is dead, who will rule and run this Caliphate, there can be only one :)

These ISIS characters, from what I've seen, spend a lot of time researching whatever target (city/town/province) they're planning to attack, to be sure there's an infrastructure in place should they be victorious. And, it looks like they planned very thoroughly what form their hoped for expansion would take. Bottom line is that they've decided to go with a completely decentralized formation. Again, very smart on their part.

Anyway, I didn't mean to go into this too much. It's just that I think the odds of a breakdown in ISIS'S effectiveness is just 50/50 if Baghdadi is out of the picture.

p.s. Since I've gone this far I might as well go a little farther. The key to defeating ISIS is definitely not in a military shootout. Like I said, ISIS is decentralized, and plans to fight in, more or less, an asymmetric, guerrilla style of warfare. As we know from history, regardless of how much bigger, and powerful, one side is over the other, that style of warfare takes a long, long time to be defeated. This is what Lincoln and Grant feared the most as the Civil War was coming close to the end. Some military experts estimate that the South could have held out in some fashion for several years if Lee had decided to go that route.

The key to defeating ISIS is MONEY; cut off the supply for a specific period of time, and they're finished. Decentralization has been very successful for them so far. But, decentralization also means they have many, many semi-autonomous units, each with a lieutenant who's (relatively) highly paid, and, probably very ambitious. ISIS has a pretty sophisticated financial, incentive/reward system for these guys. If their cash flow is interrupted for any length of time you can expect a lot of these guys to become disgruntled, and, disillusioned, pretty quickly. They've been indoctrinated to expect a reward based career, and not so much an ideological one. That's one of the main reasons they've been able to recruit so many officers from so many different countries: Iraq, Syria, Libya, and outside the M.E.