Why can't several games be successful? I know there are only so many gamers in the market, but a game doesn't need 11 million subscribers to be fun or profitable. Your game doesn't have to beat every other game for it to continue to be developed. Some games might not appeal to you yet appeal to others and that's fine. Competition is a good thing in this case as it prevents developers from getting lazy; it encourages innovation.
I want every game to succeed, even the ones I can't stand. I want the hardcore PVPers to find a game that makes them happy. I want the sandbox people to find a game that makes them happy. Etc. I don't see them enjoying a different game as a threat to my game. If my game succeeds I want it to do so based on it's own merits, not because all the other games "failed".
Thanks to Derek Thorson for helping create the coexist logo. The letters are from the logos of World of Warcraft, Dungeons and Dragons Online, Lord of the Rings Online, Final Fantasy XIV, Guild Wars 2, Star Wars: The Old Republic, and The Secret World in that order and are property of their respective owners.