Well, we know that the supposed meet up between "new" Superman and "old" Superman has either been put on hold or taken out of the books altogether. Whether or not this has any connection to Rebirth we don't know. We DO know that the Golden Age JSA is coming back in some form or another. Current speculation says that Rebirth is anything from a hard reboot to merging of "new" versions of characters and "old" versions. What little we do know is that it's supposed to be designed to make the books more in line with the movies or at least other franchises. Now, not having read every article on the subject, do we know anything else?