On his blog, R. Scott Bakker confirms he has completed the first draft of The Unholy Consult, the concluding volume of The Aspect-Emperor trilogy and the sixth book overall (of eight or nine, which remains to be confirmed) in The Second Apocalypse series.
Extensive rewrites will now commence, with Bakker estimated that about a quarter of the book requires some attention. The current draft stands at 300,000 words, making it substantially longer than any other volume in the series (the previous-longest, The Warrior-Prophet, clocked in at 205,000). However that word count might come down in rewrites. Bakker also confirms that The Unholy Consult will effectively conclude the story arcs begun a decade ago in The Darkness That Comes Before, so that if the final sub-series is not written or published there may still be some sense of resolution in this volume (though I wonder if this is really the case).
With rewrites and editing still to come, a publication date for the book is uncertain. Late 2014 would appear to be theoretically possible, but 2015 may be more likely at this time. In his comments Scott suggests a possibility of the book being split if the length does not come down significantly. Let us hope this is not the case.