That dynamic has changed a lot with multiplayer games which are in continuous development. For instance DayZ just hit record player numbers after nearly a decade:

https://www.reddit.com/r/dayz/comments/11nlu70/recently_dayz...

But even if that's an outlier, online games can have a surprisingly long tail where the game remains profitable even if the player count doesn't grow anymore (as long as the developer supports the game at least).