When Should DLC Become A New Game?

Valve's announcement today of new DLC for Left 4 Dead got me thinking. How long should a developer continue releasing new DLC for a game, and when should they start banking their ideas for a sequel? Share your opinions in our reader discussion that looks at the timeliness of downloadable content.

Let me start by saying that I think it's great Left 4 Dead 2 is getting more DLC; the game hasn't been out that long, and Valve is awesome about supporting its games with quality post-release content. But even when I'm interested in a game and feel compelled to check out its DLC, part of me wonders if the development of that bite-sized piece of bonus content is taking away resources from a future project. Fans would probably raise a ruckus if Valve announced a Left 4 Dead 3 any time soon, but if a third installment of the series could provide a significantly better zombie-slaying experience or mind-blowingly awesome graphics, I would buy it tomorrow -- and I would rather they started working on it immediately, instead of giving us more of the same (however fun it might still be).

There seems to be some kind of expiration date for DLC, where a game just doesn't seem to be worth returning to for a bit of new content. I'm not sure how much time needs to elapse -- a few new L4D2 maps are fine, but I wouldn't want to play another expansion for Fallout 3, even though its DLC packs have been great. Online shooters may be the exception; Team Fortress 2 has had more than a hundred updates and is still going strong, and I'd just about kill someone for new Bad Company 2 maps at this point. I'm sure if a new Modern Warfare 2 map pack came out tomorrow it would sell like hotcakes as well. 

So I leave the question to you: At what point would you prefer a developer stopped supporting an old game and started creating a new one? Are you looking forward to the new Borderlands DLC that was recently announced, or would you rather play a Borderlands 2 that much earlier? Share your thoughts in the comments below. Also, check out Tim's recent feature on games that got post-release support right.