From Sanderson’s blog:
TOWERS OF MIDNIGHT is going very well. I’m very pleased with how it’s turning out, and I’m confident it will be ready in time for a release later this year as promised. It will be longer than THE GATHERING STORM, which is another reason the progress bar stopped. I’m just not sure how long the book will end up being, so a percentage is harder to judge right now. The actual length of the book right now—after putting together all the pieces I’ve been working on over the last six months—comes to 291,294 words. THE GATHERING STORM was around 300,000 words. I estimate this one at around 320,000 or so after revisions and edits. (It might get as high as 350,000, then get sliced back down. I always trim a lot off books in later drafts when I tighten up the language.)
[Another] thing that happened in December to slow me is that production from Tor started to get anxious because they didn’t have THE WAY OF KINGS (book one of my new series, The Stormlight Archive) in final form yet. So I had to spend a lot of time working on another draft of that book, along with getting some of the interior artwork done.
Sanderson’s a damn workhorse, there’s no denying that. It’s obviously good news that he’s within the final 20-50k words on Towers of Midnight, though, as he mentions, his revisal methods are incredibly in depth, so its hard to put a finger down on just how close to completion the novel is. It’s almost bizarre to consider two Wheel of Time novels being released so close together. Still, with his work ethic, it looks likely that The Towers of Midnight won’t have a problem hitting its Spring, 2011 release date. One wonders if it’s not too late to sneak it into the 2010 Holiday season (which Sanderson hints at). Big bucks, there.
What I’ll be curious to see is how his production continues once The Way of Kings is released, and he has to start writing his original material alongside the Wheel of Time novels. One can only assume that we’ll see a bit of a gap between The Way of Kings and the second novel in The Stormlight Archives.