I don't think it's that simple. There are too many people ready to take the places of the "martyrs" and it's a fight that will never be won. The more stories of bombings and killings,the more "volunteers". Merkel and the idiots who run Europe have opened the doors and made cross border travel way too easy and it's too late to stop it now. This will be an ongoing war. Look how it is stirring hatred on here.
IS are tactically very competent. They have attacked tourist destinations to ruin their economies, make more young people disenchanted and more likely to join them when they have no money, they have got people scared of visiting places, scared of visiting sports venues and shopping centres. This will hit economies and economic growth which affects the western countries. They are stoking up the far right and the tub thumping Amercian politicians (some) and this is exactly what they want to happen. They have grown extremely rapidly.
Unfortunately Western governments as always didn't respond to the threat quickly enough and it's now become a huge job. In my opinion there will be troops on the ground in Syria in the next 3-6 months and they will be Russian. Where it goes from there, who knows.