If you BUY something, you OWN it. You can do whatever the fu*k you want with it. Sony would commit suicide if they ever even hinted at implementing this.
GameStop doesn't rip you off.. You don't have to sell your game to GS.. But you do bc your game collects dust and bc it's not a lot of hassle.. If not, keep the game for years and never get anything back for it.. Which would suck. If I can get 35 bucks back for a game I've already played and beat, I will never complain... And usually I can.
Just because you bought a PS3 doesn't mean you OWN it. When you buy a gaming console or a game that goes to said console. You are only being LICENSED the console/game. You bought a copy of the game, and the right to play said game on said system. Other than that, you have no rights. If you bought a copy second hand(meaning Sony/MS didn't license it out to you), Sony or any company for that matter has the right to deny you the ability to play it. They just haven't acted on that right up to this point. The same can be said for the movie industry.