Everybody has worries, even Turbine's executive producer Jefferey Steefel. While we don't know what worries him, we do know what doesn't: World of Warcraft. In an interview with MTV Multiplayer, Steefel revealed that Lord of the Rings Online didn't see much of a dent from Age of Conan or Warhammer Online's launch. In fact, much like World of Warcraft, Steefel says most players who left eventually came back. This definitely explains why he's not worried about Wrath of the Lich King and it's launch a week prior to Mines of Moria -- he's got numbers to back it up.
So what's the big secret? Is Turbine employing the power of the one ring? Well, according to Steefel there's a couple of reasons, "Somebody who's really looking for that heavy [Player vs. Player] or [Realm vs. Realm] experience, they're going to go play 'Warhammer.' But if they're looking for the best [Player vs. Environment] game, it's clearly 'LotRO.' Period. Plus, it's 'Lord of the Rings!'" Seems like a solid argument, although none of it would matter if Lord of the Rings Online wasn't an incredibly well-made game.
Steefel even points to this fact when asked why games like Tabula Rasa fail while others succeed, saying, "Consumers aren't so forgiving anymore, and I think that's why [MMOs] are starting to have difficulty." Blizzard certainly played a role in that, although it was bound to happen with time, anyhow.