It seems reasonable to think that the face shots shown are actors who are able to return in future episodes.
I am a fan of Booster Gold from the comics but it seems a waste of time to do an episode with him at this point. Also a waste of Geoff Johns single writing assignment this season. He introduced Hawkman it would have been nice if he could have written his final episode. Also there is the issue of the hidden JSA members which will never be resolved.