Apparently, a film could be a possibility after this final season.
Bryan Cranston has hinted that the series may continue after the season 5 finale, stating "Vince (Gilligan) feels that now we have too much story. We could actually go beyond those 16 episodes. It's not far-fetched. I wouldn't mind visiting that possibility. And this is coming from a guy who doesn't know anything of how the show's going to end. If it doesn't end up in a total apocalypse, who knows? Maybe we could revisit Walter White a year down the road and see where his life has gone. If he's still alive, that is."