I’m starting to think that the reason we’re leaving is that we don’t want to be around the neighborhood when the (well-deserved) bloodbath of ISIS takes place.
The major blood bath for ISIS is long since passed, and we dropped most of the bombs on them for it. Mosul, Fallujah, Raqqa were all much, much bigger than what is left.
Basically, we are coming to the end of ISIS holding territory (with the ability to tax locals) or standing as a military force with heavy weapons. It looks like just a few weeks left, and they will be reduced to small guerrilla cells hiding in territory controlled by other authorities. No further need of airstrikes or artillery support, they will be hunted by local police and security services.