1) Games in different genres have wildly different resale values. Sports games are all but worthless a year out, as they’ve been replaced by the next season’s games, with all their attendant roster updates and micro-improvements.
2) Games with the *most* replayability keep their value – RPGs and fighting games. I suggest that many people purchase games in these genres knowing that they’ll retain value on resale, the same way that consumers look at potential resale value when purchasing a new car. This means that publishers actually see increased revenue because of the resale market – specifically, they’ll have sales they otherwise wouldn’t because the perceived risk in purchase is much lower.
3) Downloadable content will kill the golden goose. Eventually, the hard drive space and bandwidth will be there to allow for a user-acceptable experience in downloading 50GB. That’s a given. However, eliminating the ability of people to reduce perceived risk by eliminating physical resale will destroy the industry. If we move to a downloadable universe, we will lose the many types of games we have now. Even with Steam and other download platforms for PC, the PC gaming market is all but dead. All that are left are casual games and MMOs (either subscription or freemium). The PC hardware for these games aren’t the souped-up gamer rigs. The PC hardware for MMOs is subsidized by the fact that the same PC will run Office just fine. There’s no cross-utility subsidy in console gaming; the risk of purchase will be higher, meaning fewer sales will occur. The notion that bypassing retailers for digital distribution will put more money in publishers’ pockets is beyond moronic – it’s insanity (doing the same thing and expecting a different outcome).

Cheers,
Sachin

(Disclosure: I run Dawdle.com, a dedicated online marketplace for new and used (yes, both) video games, systems, and accessories.