Bryan Cranston, AKA Walter White AKA Heisenberg, was on CNN yesterday promoting Godzilla when, unsurprisingly, Breaking Bad came up. Considering the massive success of the show, it is to be expected that Cranston will be answering BB questions for years to come.
CNN's Ashleigh Banfield asked Cranston if Heisenberg will ever return, the actor responded "never say never....hey, you never saw bags zip up or anything, or anybody say...you know."
But Breaking Bad fans shouldn't hold their breath. A return from Heisenberg would likely degrade the integrity of the original run. Creator Vince Gilligan, while doing press for the final 8 episodes, said multiple times that he did not want to stretch the show out just to get more seasons and that he did not want to overstay his welcome.
However, that is not to say that Walter White wont show up in the upcoming prequel Better Call Saul. I, myself, don't think Cranston's comments hold any weight to them; he has been known to say very tongue-in-cheek things during interviews.
Bryan Cranston and Dean Norris Breaking Bad Audition Tape: