According to a press release [March 31st] from Tor/Forge Publicity Manager Dot Lin, the details are set for the final, posthumous book in Robert Jordan’s bestselling Wheel Of Time fantasy series. One of the big revelations: that last "book" [A Memory of Light] is being split into three volumes.The rest is at AV Club.
EDIT: From Brandon Sanderson's (the guy who took over after Jordan's death) blog:
April 2008. I had to make a decision. I realized that the book would be impossible to do in 200k. I'd begun to say on my blog that it would be at least 400k, but even that seemed a stretch. I looked over the outlines, both mine and Mr. Jordan's. I stared at them for a long time, thinking about the book. And this is where the first decision came in. Did I try to cram it into 400k? Or did I let it burgeon larger?
To get this into one book, I'd need to railroad the story from climax to climax. I'd have to ignore a lot of the smaller characters--and even some aspects of the larger characters. I just couldn't justify that. It wouldn't do the story justice. I cringed to consider what I would have to cut or ignore.