^ as regards the weary and tired point, I did say in my original post that perhaps the end of the movie would see him reinvigorated, so we've sort of come full circle. But it's not just a mental thing - what if he's physically worn out and past his best? Being Batman is more demanding than being Jim Kirk! Still, I suppose its unlikely they'll end it with him hobbling off on a Zimmer frame.
I still don't see the problem. The filmmakers are in control of whatever happens in the film. They want a Batman who can carry a franchise, so of course they won't have him physically past his prime.
Although, heck, Nolan had Bruce physically past his prime at the start of TDKR, even had his back broken midway through, and then just handwaved him back into shape in time for the climax. Filmmakers can do whatever they want with their characters, even when it makes no sense.