That's why I said extreme case. Even if people sold games only after having finished them, the consequences would be tremendous. So tremendous that it'll never happen in a large scale: either downloadable games are somehow made excempt via some sort of contract, or games will continue their shift towards being SaaS, ie. you may resell Diablo 3, but you can't resell your Battle.net account which is strictly required for playing the game.
The publishers in the US hate the retail used games market with a fiery passion (and it's not hard to understand why). And by and large I think very few people make use of that, most people -- I'm extrapolating from myself here -- are going to be too lazy to carry their games to GameStop for a couple of bucks, and most buyers are going to be too wary of complications with a used game to save a few bucks.
A digital download used games market would be way more convenient for both sellers and buyers. It would also be much cheaper to both start up and operate for a middleman, who could get by with much a lower cut than GameStop.
There's one difference between pirating games, and buying used games. Pirated games make perceived value of a game smaller - because you have alternate source to get it for free, AND you get DRM in your game, making it less convenient to use than pirated version.
Possibility to easily sell used game may make perceived value smaller (there's cheaper legal way to get a copy). But it also may make the perceived value bigger - if I can sell game after finishing it - I can get back some of the costs, so I can justify buying more expansive game in the first place. I know kid that routinely buy legal games, play them, and sell them at Polish equivalent of e-bay. If it wasn't possible, he would buy much less games, cause parents only give him so much money for games.
I don't know which way the perceived value will go, I'd guess it's self balancing - the easier and more popular selling used games is, the more perceived value of games will rise, making it possible to rise the prices, but also making used games more popular.
Anyway IMHO the entire information market (games, apps, music, movies, ebooks, etc) is going to be mostly honour-based in the future, at least for things that can't be made into services. The only thing that makes people pay you for your content is their feeling that they owe you something. Make them angry at you, and that feeling disappears. One great way to make your clients angry at you is to use law to enforce "unjust" conditions on them. And I don't see why selling used licences is ethicaly different from selling used books, so it may be hard for publishers to persuade people it's actually Evil.
>downloadable games are somehow made excempt via some sort of contract //
You can't force a license on someone that reduces their legal rights in this way, it's not lawful. It appears they'll be able to apply technical means to make it difficult (as impossible as they're able) but they won't be able to use a legal remedy to inhibit lawful resale.
The publishers in the US hate the retail used games market with a fiery passion (and it's not hard to understand why). And by and large I think very few people make use of that, most people -- I'm extrapolating from myself here -- are going to be too lazy to carry their games to GameStop for a couple of bucks, and most buyers are going to be too wary of complications with a used game to save a few bucks.
A digital download used games market would be way more convenient for both sellers and buyers. It would also be much cheaper to both start up and operate for a middleman, who could get by with much a lower cut than GameStop.