It is commonly known that GameStop makes a killing off its used game market. Gamers trade in x number of games for some credit. GameStop turns around and sells those games at 300% profit and the gamer turns around with their in store credit and uses it to buy new or used games. It is a similar operation at Amazon, Target, TRU, Hastings, and the list goes on and on. This generation has tried to make buying new on day one as attractive as possible. Exclusive DLC for early adopters, requiring one time keys to play online, offering special trade in deals on old games for the new AAA title (something GameStop really pushes), and throwing all sorts of pre-order bonuses at gamers.
If the new 360 cannot play used games, and the lock out method rumors include some sort of chip on the disc itself or something with the console. Who knows? Operation Flashpoint on the PC carried a message that if gamers pirated the game the copied disc would become unplayable
What about game rental services like Gamefly or Redbox? What about game trading sites like Goozex? Would they go along with GameStop and Amazon and focus on the previous generation?
In regards to consoles locking out used games, if the PS4 and the Wii U can play used games, gamers may hold off on buying a new Xbox and instead turn to the PS4 or possibly pick up the Wii U.
If none of the consoles can play used games I could see the price of games coming down. AAA titles may come out at $45 or $50 instead of $60. Retailers might give out more $10 giftcards, or have b2g1 sales more often.
Don’t like buying used games now? There is nothing wrong with that. I support this idea on a semi regular basis, especially for smaller studios. I wait till the games drop in price. Once a game hits the $20-$25 mark and I am interested I usually pick it up. Better yet just hold off until Black Friday. Some of the recent price drops I have seen are Assassin's Creed III for $25, Resident Evil 6 for $20, Borderlands 2 for $30, and Paper Mario: Sticker Star for $20.
PC gaming is an entirely different topic. That is an industry where pirating has been going on for years. Although they have tried to combat it with CD keys etc, PC games are getting so cheap digitally that it makes sense to just buy them. A good example is Resident Evil 6, it is $20 for PC on Amazon, and $30 for PS3.
If the next generation of consoles lock out used games, I think more gamers will move to the PC. But for now this is all a rumor. Personally, I think GameStop will still be around for years to come no matter what happens to console gaming.