Realistically, the goal of the Batman mythos was, as I understand it, that one man can make a difference. However, it was that he kept making a difference and, specifically, that copycats were bad, mmm'kay. Nightwing, Batgirl, Robin, etc. were given a pass because they were "family" and always aligned with Bruce. Bruce literally has no one in the Nolanverse; the love of his life was killed by the Joker and the rest of his colleagues are either older, mentor figures or not capable (Gordon; plus older). However... I have theories on the film; very similarly to Cabin in the Woods' trailer/commercials where we're decidedly not seeing even remotely the coolest bits of the film or the true story of the narrative. And those theories do not involve Batman dying.