>If he or she wants to play it without the disc then they need to buy a new code.
From who? A used game code? Or a new one? How is that any different from the rules announced at E3 with no used games?
>Person B plays the game as much as they want then lends the game to Person C. Person B can no longer play the game because they don't have the disc, but Person C can play the game as much as they want.
So the disc is required to play? Like in the new rules?
They'd buy the code from the people that made the game, of course. If you want to install the game to the console and play it without a disc present then it's trivial to process that through a workflow that requires some sort of purchase.
You can have the best of both worlds if you like.
If it makes it any simpler just think of it as downloaded vs. disc-based games. You can pay to download the game to your console or you can play the game off of a disc. For convenience you could include a free download code in each new game, or even just provide a discount.