Isis itself is fundamentally weak. Unfortunately, however, most of the forces opposing it are the same, especially the Iraqi army, and the Assad regime, which in itself is nearly as morally terrible. To think that Isis has some irreversible stranglehold upon the region is not true, though I doubt they will collapse within the next few years. Still, there are only so many fighters they can recruit, and they face opposition from every major force in the region and abroad (though many of those forces have yet to engage in any meaningful way). They're fighting a losing battle, but it may be a battle that lasts quite a while, and that will still likely inspire the weak and the desperate in the west to launch more lone wolf attacks.
As Peh noted, however, the removal of Isis won't suddenly make the situation in Syria any better, or cause the Iraqi factions to come together in a communal hug. War will continue, especially in Syria.