They'll do something because as it stands 'The Man of Steel' is the only DC movie they'll have to lead into this. Every Marvel movie was doing this from the beginning. I think they've got to do something similar to get attention to the film.
Thing is, they haven't yet announced if Cavill will be the JLA
Supes. It's almost as if they're waiting to see how MOS
does before making that call. They've got to be planning on having him in a MOS2
at the very least, but look how that worked out for GL2