Well, their biggest success is pretty much done to death now. NGE has had a series, multiple OVAs, multiple movies, multiple revamp movies... there's really not much else to get out of it unless you want to tell the story of how they got into that mess to begin with, which might be the most interesting part of all of this to its core fanbase given their age. Maybe tell the story of the project up until Shinji's mom dies or something.