According to a Remedy letter to Joystiq there will be a new Alan Wake soon, but it will not be Alan Wake 2 or new DLC.
The Remedy Announcement:
So referring to your most recent Joystiq post ... It's awesome to hear you say that Alan Wake appears in your hearts. I've read through all the responses on your site which is fueled with positive responses. It really would seem Alan Wake is very close to the hearts of the fans out there, and to ours too. To that point, it's a shame that this news leaked before our official announcement which will of course include the visuals and information to support it. Well, now that the cat is out of the bag, we owe it to you and the fans to shed a little more light before we get the chance to officially show them what the guys have been up to.
Fans of the franchise will be excited to learn that yes, more Wake is coming! But to be absolutely certain to avoid confusion, this next Wake installment will not be Alan Wake 2. But neither will it be DLC. The rest we're saving for our official announcement when we'll actually SHOW YOU.
We are really excited about this project which a slice of our team has been working on for the last months. It's something that'll definitely give more to the Wake fans out there, but just as importantly, this installment will also give an opportunity for players who aren't familiar with the franchise to finally jump on board.
We can't wait to show you more, bear with us. Release dates, platforms and pricing are unconfirmed as of yet, but Fall 2011 is probably a good guess. More coming soon!
So keep your eyes open for more news on this later.