I've been quite out of the loop lately and just saw on Ultan's Library that the next Gene Wolfe book, A Borrowed Man, has been listed on Amazon with a release date of October 20th, 2015. According to a recent interview with Robert K. Elder of the Chicago Tribune he's also already started writing the book's sequel.
A Borrowed Man on Amazon
A Conversation With Gene Wolfe on Chicago Tribune
The interview gives mention that he's still open to returning to the Urth Cycle universe. As I finish up my 3rd read of the Books of The New Sun, that's something I would definitely appreciate seeing. His world building is nothing short of incredible.