We seem to easily draw
maps of their territorial borders.
They appear, to me, to be a country of Sunni Muslims banded together for a genocidal crusade.
They hold those of others under the threat of death or torture. You could pull a Dresden on those cities, kill some ISIS people and kill 90% of the rest of the population who just jump when ordered to stay alive. We'd kill far more than ISIS has. Sorry, I can't endorse that.
For me it's not a notion of body count, but of ISIS extinction. "Pulling a Dresden" would most certainly end their threat to the world.
The alternative to that brutality is... what, precision strikes on known militant targets, while someone's military rolls in on ground and parks themselves on the streets waiting to provoke a response? That has to be a permanent troop presence. Ours? I can't endorse that.
Do we really expect the Iraqis to pull through after losing a very important half of their country? I expect to see them settle for present borders, leaving ISIS officially a new country. Or maybe take the Pakistani route of declaring them... tribal areas.