I didn't say they couldn't sell, but apparently Didio seems to have a serious issue with the Fab5 generation of heroes. Look how long he held out from putting them into play with the New 52...it wasn't until Rebirth and I am not sure that didn't have more to do with Geoff Johns than Didio. See also that once Geoff was removed from his position, storylines that seemed to be in play with the characters (specifically Wally) were seemingly sidelined and now two of them are killed off in an event book while Nightwing is for all intents and purposes no more either.
These characters obviously can sell...they were the top selling book of the 80's and to say they have lost their ability to sell...then what keeps characters like Batman, Superman, Spider-Man, Wonder Woman, Avengers, Justice league in print? It's the publishers willing to put the best talent on the books and allow them to work. Titans hasn't gotten the best talent in many years. Maybe Bendis will pull them under the Wonder Comics umbrella...it might be the best thing for them.