Mistershine on 05 June 2013
They already said that if you buy a game and your son goes to a friends house he will be able to play it there because of the family account thing. So in theory all you need to do is setup a guest account for the second Xbox. Currently XBLA ties your game to the first console you buy it on but lets you play on any console as long as you sign in to Live, so even if it used this method you could just buy the games on the secondary console and use them on the main console while logged in as you.
