Re: Stuff you like to believe happened in Nolan's series
One of the issues the film has and maybe this belongs in the "what you would change in hindsight" thread but Bruce's retirement is problematic because he seems in really good shape when he returns. In fact, other than the first Bane fight we never see him struggle as Batman. We really needed to see that he isn't in his prime as Batman, it would make his retirement easier to understand other than wanting to be happy - he also literally can't do it anymore. When he makes it out of the pit, it seems he has become stronger than ever so it's kinda weird for him to just stop at that point.
After multiple viewings, you can interpret that ending to mean a lot of different things. It's possible Bruce has faked his death and left the cave to Blake to watch over it while he lives his life with the intention of coming back as Batman with a Robin if it's ever necessary again.