In the comment section for my July 3 post, sage RAW scholar Royal Academy of Reality 1132 says, "I keep waiting for the Library of Dreams to get in my copy of THE WORLD TURNED UPSIDE DOWN. I've had it on reserve for weeks."
Haven't we all. RAW had originally intended to write five "Historical Illuminatus" novels, but the fourth, THE WORLD TURNED UPSIDE DOWN, was never written, or at least never completed.
We're also in for a long wait for BRIDE OF ILLUMINATUS, the sequel to ILLUMINATUS!, although according to this Wikipedia article, an excerpt was published in Wilson's magazine, Trajectories. (PDF is here.)
TALE OF THE TRIBE, which concerned the Internet and no doubt other topics, also never came out. I would love to have read it.