I am going to be clear as day here. As much as fans want to see a continued story with John Blake as Batman it will never happen. I think tons of fans missed the undertone message of the trilogy, Batman can be anybody. As a person you can be destroyed, but as a symbol you can be indestructible. Realisticly I think John Blake wouldn't be as good of a Batman as Bruce Wayne. Bruce Wayne was trained by the League Of Shadows for starters, so he had a necessary training background to combat multiple people and use darkness effectively. He also had unlimited access to gadgets through Lucius Fox, and also help from Alfred in times of need (Like when Scarecrow poisoned Batman and set him on fire in Batman Begins, Alfred rescued him) John Blake has little to no combat experience, nor resources or financial backing that Bruce Wayne had. If you think about it, I don't think that John Blake can just walk into Wayne Enterprises and ask Lucius Fox to take a peek at the "off the books" armory. Even if he did it would be more suspicious than usual. John Blake would be on his own, and frankly would probably get his ass kicked.