Yes, jihadis will go underground in Iraq and Syria to function as more traditional Islamist terrorists following the defeat of the caliphate.
And some jihadis will go back home or disperse to new targets for the jihad. Some of those will become terrorists in those countries.
Others who disperse will be discouraged and will drop out of the jihad. Some of those can be turned to fight those who continue to fight, whether in Iraq or Syria, or elsewhere.
And while one can find analysts who claim that dispersal is a bad thing, it is a better thing than to have them with their own proto-state. Sure, I'd rather kill them all where they stand while they try to hold their caliphate, but life is imperfect.
And there is one more advantage to jihadi dispersal.
While many countries don't cooperate that much in a coalition of the willing to fight jihadi terrorists "over there," when the jihadis come to them, these less enthusiastic defenders of civilization against the jihadis find they must join the fight as jihadis come to them.
Yes, that anti-ISIL meeting will have more attentive participants now:
The Trump administration is to host a meeting of minister from 68 countries focussed on taking forward the battle against Isis.
And don't forget that these really are barbarians deserving of no quarter in this fight:
Islamic State fighters dressed as doctors stormed a military hospital in Kabul, killing at least 49 people and wounding dozens more during an attack in the diplomatic heart of the Afghan capital.
Am I really the heartless one when I say the only good jihadi is a dead jihadi?
Anyway, to avoid things like that, reluctant allies will be in the fight.
I'm not saying I welcome the new threats to countries and their people. But I am saying that they will become new allies in the fight against jihadi terrorists out of necessity.