I was thinking about that too. If they were to do more, something interesting might be that each episode could be a short story. Like something that happens to the characters in the future (family life, another fight, ect), elaborating on a past event or childhood (Iroh and Lu Ten, more about Katara's mother), or stories about past avatars (how Kyoshi started dressing in her warrior garb, showing more of that female air avatar, ect). They could even animate the comic adventures! Depending on the episode they could either take up the whole episode, have two stories to an episode seperated by a commercial, or something like The Tales of Ba Sing Se.
What do you all think of that idea? I know it breaks the mould of the past seasons, but now that the main story is over, the possibilities for new short stories are practically infinite.