I believe there are still KFOR forces in Bosnia. Not sure if US forces are among them, but probably.
When I was there in 2004, things were already winding down a good deal. We were closing Eagle Base. Mostly just a tiny remnant of NATO forces there hunting down PFWCs (war criminals) and trying to find and destroy weapons caches.
I'd LIKE to think after 8 years of "winding down" that we are actually out.
But I have no evidence to support that thought.