First, I'd love to hear from bitbook as to the reason for shutting down. Second, I've been looking for a replacement and so far, I've tried nitrogen (feel free to use my link!
https://nitrogensports.eu/r/12155). I'm not sure I'm 100% sold on it yet. I just deposited a small amount and put in my first wagers for this weekend. We'll see how it goes. I'd love to hear if there is a better book out there...