Re: A theory about an alternate TDKR with the Joker
If Heath had lived, there is definitely a possibility that Bane might never have shown up in this trilogy. Hell, I don't even think Nolan would have ended this trilogy the way he did if Heath had lived - Bruce would have most likely come to the conclusion that he is Batman for life, and there is no hanging up the cape and cowl.
Nolan probably would have used one other villain to supplement the Joker in an alternate TDKR. If not Bane, then my hunch is that it most likely would have been Hugo Strange.
Speaking of Hugo Strange, any remember those rumors way back in 2010 about TDKR being based on Prey? Those were interesting times, to say the least.