In before someone denounces this as some greedy fascist corporate statement bluh bluh industry bad bluh bluh consumers are always right bluh.
EDIT: Never mind. Got ninja'd on that one.
While single-player only games are far from dead (Alan Wake for instance), he is probably right that they tend to make up more of the pre-owned market. You're more likely to give a game up if there's nothing to do once the story is done, especially if it's one you don't feel like experiencing again. People may complain about tacked-on multiplayer modes, but in the end, those same multiplayer modes are probably a calculated decision made to try and retain as many consumers as possible.
The whole thing regarding book swaps and yard sales isn't really analogous. From my limited knowledge, movies make their money on the silver screen (mostly) and from DVD sales (a only a little bit) from the fans who want home copies, so they're not really affected all that much by their rental industry. Books in the meantime seem to be doing better than ever, especially with the advent of e-publishing, and book publishers don't really have to compete with a "used book" market. The only thing vaguely similar are libraries, but those function in such a different way that the situation really isn't comparable. And (from what I've observed), book lovers tend to retain their products, even if they don't really care for them so much.
Because videogames make the bulk of their money in the first two weeks of sales, used game retailers have much more of an impact on the industry than their proponents are willing to let on. It's as if theater movies had to compete with their own rented DVDs. Would it kill the industry? Probably not, but it would have a measurable impact on the way movies were to be produced.