Interesting coincidence... I just went to a talk by MIT professor Sherry Turkle where she mentioned that publishers were questioning if the 'longform' of her book (~17,000 words I think) could actually sell. Her answer was that the only way to adequately deal with the complex issues she addressed was in this format.
17,000 words is not a long book? was that supposed to be 170,000? Or just in the sense that she wrote a long article and is trying to pass it off as a book?