I thought the set up for future Green Lantern movies laid forth in the first was actually done well, but the studio pulled the plug. Considering how the studio treats the movies, we have to worry. They need to know they are beholden to the fans on a much deeper level than if they are making a regular movie.
The only thing WB has really done right in the last several years is Harry Potter. It's much easier for them to adapt a specific book than it is to adapt a vague idea of a plot from a diversely written 75+ year old super-verse.
If I were WB at this point. I would just hire 10 of DC's best writers and tell them to create a special Graphic Novel series that will be the basis for the future movies. They pretty much have to just regurgitate the existing plot-lines, but do it in a coherent way with real continuity. You create the DC bible, and then you develop it from there.
You can't have some fucking eccentric execs putting their input everywhere. Won't work.