Worldly Andre,
I would definately take him to your college and show him around. Anything you can do to open up the world to him is going to be so helpful to him in the long run. That's what High School is supposed to be about, discovering the world around you, your possibilities, your likes and dislikes, and becoming a socially adept person!
I'd also look into the requirements for graduation in your local area. Even if he doesn't go to public high school, some areas will allow home schooled kids to graduate, or at least take the GED test, when they are finished with certian course requirements. And imho, it will keep the kids focused on some type of structured learning program, if they have some standard to fulfill.
And keep talking to him, ask him what interests him, what he wants to be when he grows up... so he feels like he has possiblities in life beyond Pioneering or Bethel Service....
Good luck to both of you! He's lucky to have you on his side!
GGG