You cant keep Bane alive. There's no chance in hell the writers would do that. That guy gets thrown in prison and either one of his mercenaries gets him out or he gets out on his own. Even if he was in pain because of the mask and locked away, you cant have both Bane and Joker out in the world. I saw the realization on Bane's face that Batman had won, when Batman was staring at him and Bane asks "I broke you, how have you come back?". That was enough for me. He got the death he deserved in my opinion. Blown down the hallway with a hole in his chest.