As you will know from earlier in the film, Caine's Alfred gave a heart-breaking monologue to Bruce Wayne where he told him that during the seven years Wayne had left Gotham since the previous movie, Alfred had an annual holiday in Florence where he sat at the same cafe and had this "wish" (or dream, or in reality... ILLUSION) that he would see Bruce Wayne at a table with a wife and enjoying a happy life away from Gotham and Batman. Alfred says he hoped their eyes would meet and they wouldn't say anything to each other but they would both politely nod, knowing both were ok. That was his illusion. So the way I took that scene at the end of the movie is that Alfred, who we just saw moments earlier completely distraught at Wayne's passing, was visiting Florence again and was once again deluding himself that he saw Bruce Wayne, alive and well, and happy with Selina Kyle, away from the cape and cowl. Chris Nolan does this a lot in his movies, you have to remember the P.O.V. of the character we are following. At that point we are following Alfred, so we have to presume this is from his mind, and the grieving Alfred has once again come up with the illusion of the impossible... that Bruce Wayne survived a nuclear blast at ground zero with a six mile radius and is happy out there somewhere with his new lover. Alfred has deluded himself so much and realises that he was wrong and that the world needs Batman, that he restores the bat signal and gives the coordinates to a new orphan who will become the saviour of Gotham (John Blake). The truth is and I'm absolutely certain of this, in Chris Nolan's vision... BRUCE WAYNE IS DEAD! He has killed off the character, giving him the ending he only knew how for his final chapter in the Batman saga should end. No matter what happens at Warner Bros in the next movie, whether they decide to hire Zack Snyder after Man of Steel or some other director and they have Joseph Gordon-Levitt's former cop John Blake as the new Caped Crusader... maybe they call it (and they should if they go down this route) - THE DARK KNIGHT RETURNS and maybe there's a third act sequence where Christian Bale (or likely somebody else as Bruce Wayne) comes back to Gotham to help Blake out who most likely is struggling in his battle with a new version of The Joker.... this would be Warner Bros' version of that Florence scene. This won't be Chris Nolan's. In Chris Nolan's world, Bruce Wayne is dead. Whatever comes after that is at WB's request but he did it in such a way where his original reading of what really happened to Wayne can be interpreted.