Lets be realistic here.
If the kid was hiding in the house he would have been found by now.
Also why would the kid run into territory he doesn't know about. Logic points that IF he wasn't in the house he'd be somewhere that was "safe" to him. Naturally if his parents don't know about where this is, his own brothers would know where it was.
With the reports that there is something attached to the balloon (which is no longer there) it actually makes sense.
The balloon itself wasn't made to carry a human and why would it have the ability to seal inside (ie. a handle to close a hatch from within) - it clearly looked sealed when it flew.
I'd wager the kid is dead.