It was while watching the movie today that I thought about a way to bring this beloved series back. What if the new series focused was centered on the daughter of Zoe and Wash? Despite Wash's fate near the end of Serenity, Firefly lore establishes (largely through the comic book series that followed the movie) that the two of them have a child named Emma who is born about nine months after the conclusion of the movie. While that would put the character at about fourteen years old right now, by the time this idea could be put in production and the show hit the air, Emma could be a rebellious 16 year old (about the same age that River is supposed to be on the show).
This would allow for the entire cast, except for Ron Glass (may he rest in peace), to return either as regulars or with guest appearances. Yes, even Alan Tudyk could come back as Wash, albeit as a sort of "ghost"--the father that she never knew to whom she confides her fears and dreams. Meanwhile, the show could focus on both new adventures as well as play out some backstory for what has happened in the intervening years.
Don't get me wrong, I'm also fine with Firefly staying how it is. As is, when I'm feeling determined, I can watch the entire series and movie in a single day. Adding more to that would complicate matters. Still, this was a compelling series that deserved better and supposedly had five or more seasons worth of stories planned before it was cancelled.
I wouldn't mind seeing more of it.