With licensed sports games -- not something I play -- my understanding is that the game typically has a player database that tracks the real-world situation. So what you're paying for is basically the right to play fantasy games with the current year's teams.

That's got value to a number of people, I expect.

With multiplayer FPSes -- also not something I've played much of in quite some years -- my guess is that the release does something to create the demand, because a lot of player base will shift to the new release, which yanks them off the old release. So if you stay on the old release, you're only playing against people who stayed on the old release.

EDIT: Of course, the flip side of the multiplayer thing. is that if the players, as an aggegate, generally don't move to the new game -- as it sounds to me, from the little I read, to be what happened with Payday 3 -- then the mechanism works against the publisher.