There's no word on George Caltsoudas' Batman The Animated Series posters being picked up by Warner Bros as a book or a collection like the story of Juan Ortiz's Star Trek: The Original Series posters. Both guys made there posters as fan art, though the latter actually got a deal out of it with Paramount and you can already buy his stuff.
George Caltsoudas just finished his collection of Batman The Animated Series Season 1 posters and they are quite the collection. Sixty-five episodes to stare at that need to be collected or at least high-rez versions need to come out to hang on my walls.