I don't believe the Legion has trouble selling because of the far off future setting. If that was the case, I think books like Saga and Star Wars, which take place in settings that don't resemble our own too much, and that are off by themselves, would have trouble selling, too, and they obviously don't. Legion has been plagued by bad writing, bad decisions, and bad takes on the characters and the universe that the fans weren't too receptive to. The same thing that has happened to the Teen Titans. If it is to be brought back, it would do it well to be brought back with a really compelling look and hook that could hopefully cause buzz among the fans and hopefully get retailers' attention. Otherwise, people may think it would be just another throwaway attempt at those characters. So, a lot of careful planning and thought should be put into them if DC plans to bring back another book with them.