After the caliphate is crushed, the dust that crumbles through our fingers will be the next threat, so says James Comey

The so-called caliphate will be crushed. The challenge will be: through the fingers of that crush are going to come hundreds of very, very dangerous people,” Comey said at a Senate Homeland Security Committee hearing on the global terror threat. “They will not all die on the battlefield in Syria and Iraq. There will be a terrorist diaspora sometime in the next two to five years like we’ve never seen before.”
“We must prepare ourselves and our allies particularly in western Europe to confront that threat because when ISIL is reduced to an insurgency and those killers flow out they will try to come to western Europe and try to come here to kill innocent people,” the FBI director said

Comey said the same thing back in July as well