ISIS is now considered a world threat. Whether they realize it, or not, they are now being hunted. Even in strong numbers, they're the target of air strikes and their numbers will dwindle, when those constantly exposed to the violence of war either become even more barbaric, or slip away to return to an existence not marred by brutality.
Although they're considered well organized, it's obvious one of their members crossed a line, murdered an innocent reporter, and recorded the event, with the thought they were promoting their cause. I doubt seriously it was ordered by someone higher in the organization; and the world recoiled in horror. Their chances of attracting anyone but the criminally insane disappeared in a matter of minutes. They're now what everyone with sense knew they were: thugs hiding behind religion.
We probably won't hear much about it, but those that help them with their finances will become targets. Assassinations will happen; local and national governments will turn their heads; those that want their resources will find ways to steal them; and the members sophisticated enough to understand the path they now follow, will cut and run; when given the opportunity.
ISIS succeeded in making the world aware that Muslim fanatics are a threat that can't be allowed to continue. Their success will now be rewarded with a systematic elimination of those that continue with their efforts.
You may doubt me, and I may be wrong, but the majority of the people that inhabit our planet are revolted by horror and violence. Those that practice it for power are never admired, respected or considered valuable members of our species. Their death is never mourned and society breathes a sigh of relief at their demise.