Is there a way I can contact Nickelodeon?

Well they do have something set to come out, Avatar the Legend of Korra. About the new female avatar that has to learn airbending from Aang and Katara's grown son. But of course, the original characters would be a lot older and Aang wouldn't be there at all. But you're right. The story is so great and the characters so lovable that I would love to see what happens next. Maybe we can start an online petition or something.