While it's an unconfirmed report at the moment, Edge is suggesting that the next generation of Xbox console, could require users to maintain a consistently online internet connection if they want to play games. On top of this, the tech would prevent the usage of used games, thereby invalidating the multi-billion dollar market for the next-gen.
It's also being reported that blu ray games available in high street retailers will come with an activation code in order to maintain the no-used policy that Microsoft appears to be adopting. Of course this will mean that there are fewer people buying games on launch day, since many people do so in order to beat a game as fast as possible and then sell it on, making up around half of the original purchase price. Without the ability to do that, many people will wait for price reductions.
Because of less people buying early when stocks are high and with the inability to play used games, next-gen games are likely to become incredibly rare in the years to come. Once production stops, expect unopened playable copies to be worth more than their weight in gold. Unfortunately this means that unless games are re-released on future systems, or made available on other mediums, you'll find it very hard in a decade or so's time to find anything for the Xbox 720 that you can play - unless you bought and saved a copy. It just won't be possible to find one that hasn't already been used.
Of course you could get a modded console and play a used or pirated version, but you guys wouldn't do that, would you?