We've got about 2 months' worth of post-Rebirth solicitations to work off of now, so we can probably safely assume the New 52 universe will still be the main continuity going forward.
The biggest change seems to be that the pre-Flashpoint Superman will be taking over as the main Superman post-Rebirth. Aside from that actual swapping of characters from different universes, most of the other changes seem to be taking the form of simple directional shifts within the existing continuity. Batman is going to be working more closely with his sidekicks, who will once again include Tim Drake (still as Red Robin, though) and Cassandra Cain, but he'll be overseeing them alongside Batwoman. Green Arrow will look more like the classic version, facial hair and all, and his series will have a more political tone, but it's still the younger New 52 version. That sort of thing.
Basically, Rebirth seems to be taking the New 52 versions of the characters and changing things around so they have more of the classic overtones; they are, however, still the New 52 versions (aside from Superman).