Re: Next Batman Film Franchise...
I started thinking about something similar after watching City of Scars fanfilm. A trilogy with an overriding story arc. Something that you think is finished in the first film (so it stands alone and makes sense) but when you examine it, you realise there's more to it than what was seen/experienced.
The idea of flashbacks is great but how long would you expect a flashback to last? Seconds? Minutes? Half the film? Certainly there should be elements in each film that tie it all up.