Something I've wondered is that role the used game industry played to publishers: did it help them by "hooking" consumers into getting certain games? Could this offset the lower sales?
I came across this article today that described the drain as "significant".
It discussed possible ways to combat the drain, such as adding special bonuses ONLY to bought games (an idea I fairly like) or blocking off certain areas of games. I'd be guessing that, much like current PC games, the game would read a signature unique to reach machine, and shut down
(I remember reading somewhere that buying games used could save the avid gamer over 500 dollars per year, which is nothing to shrug at in this economy. And where consumers save, publishers tend to lose-- or do they?)
I have my own proposed solution for game publishers: to follow up on my previous post about online purchase of games, how about an online rental service, where players might be able to have their Xbox account charged per day of play. The prices could even be higher, because there's no overhead, and also increased security for renters in knowing that they won't get a scratched or defective disk, and that it would be impossible to lose or return late!
An additional benefit would be that it would help publishers gain direct and exact statistics on which games are rented most, and what their rent/buy ratio is (if they don't have that already). This could be valuable for measuring players' perceived "value" (or addictiveness!) of a game.
It's true that this would be more of a "if you can't beat 'em, join 'em" approach, but I think adding DRM is treading on thin ice, because PC gamers HATE it. I can even see some gamers renting just to spite publishers if they're not careful!
However, as mentioned in the article, this approach would hurt retails, who, as a whole, have a synergistic relationship with publishers. While other retailers could technically follow gamestop's new practice of selling digital keys to unlock game downloads, they would probably still be hurt as a whole.