One that I have wanted for a while (and is kind of happening) is an Eminence in Shadow story from the perspective of the characters that are not Cid. If you, as a reader, had zero insight into Cid's thought processes, then TEIS is a very dark fantasy setting instead of the comedy/parody that it becomes when Cid is there. I think the actual worldbuilding underlying TEIS and the characters that populate that dark world are interesting (Alexia, Alpha, Claire, and Rose would all be great co-MC candidates).

I said that this is kind of happening because they have announced that a manga adaptation of the Seven Shadow Chronicles is being worked on. These are stories from the Seven Shadows' perspectives during a period of time that is time-skipped in the novels. They are told in the TEIS mobile game and were written by the LN author, so are considered canon. These stories are often dark, but then each little arc usually has Cid show up and do Cid things to inject some humor.