Check out this 2011 interview with Vonnegut’s long-time agent, business manager, and friend Donald Farber.
Interestingly, Farber is asked about Vonnegut’s final, unfinished novel, If God Were Alive Today. On the question of whether or not it would ever see the light of day, Farber responds, “…of course I’ve thought about it. But it’s unfinished, and there’s no point in publishing an unfinished work. Kurt had said everything he had to say.” Farber later states, “We will not publish Kurt’s unfinished work.”
Despite Farber’s comments, If God Were Alive Today was eventually published in 2012, the year after the interview, as part of the book We Are What We Pretend to Be.