I loved The Last Airbender and Legend of Korra is awesome!!!! I'm so glad it's renewed.
Personally I hope there is another series after this one, I wrote a blog about what I would like it to be, I call it Avatar: Spirit of Earth.
http://www.ign.com/blogs/guardianike33/2012/06/23/avatar-spirit-of-earth
In case you didn't know, I have a comic book called Guardians. I'm the writer/creator of it, and we have four issues out right now, with our fifth coming out soon!
We're also doing a Patreon right now for the comic, and I'd appreciate any and all help in getting it funded. If 56 people pledged $3 per issue, we'll be funded
To pledge, click here. Please join Team Guardians!