The boy will most likely show up at a friends house or even their own home. They obviously didn't know where the kid was and what he was doing in the first place.
Shepard Smith on FOX is reporting the balloon was empty, and it was a weather balloon belonging to the father - he's suggesting they look under the bed, because this kid, if he's alive, may be scared he's going to get a wooping for messing with Dad's balloon.....