See this was my thought's of the finale before I saw it.......
I was watching the first season on my computer and Aang hadn't fealt as close to anyone like Katara since Monk Keiatsu (his old air temple master) right?
AND Aang was frozen in an iceberg for 100 years making him 112 right?
The order for the avatars is Wind, Water, Earth, and Fire so I was thinking that it might've been Katara as the next avatar. Now I know it sounds crazy but it could work. So in the finale, heaven forbid, I thought that they would be fighting the Fire Lord off from the Earth Kingdom while Zuko faced off against Azula. Then Aang would give his life for Katara and she would go beastmode with like all of the past avatars in the background and Aang would appear, I thought this because his avatar state chakra was blocked and he couldn't activate it so it was passed on, not to mention katara was the last water bender from her tribe remember?
......Then Zuko would be on the brink of death when Mae and Tai Lee would step in and together they would kill Azula
I also thought that Sukki was gonna die, Uncle was going to die, and the series would end with a older looking Zuko and Mae holding twin boys with Katara, Toph, Sokka, and the gang in the background and Zuko names them after Aang and Iroh.....And then come to find out Toph and Sokka got married, and Katara and the Earthbending kid with the mustachse got married.
This does not mean I support relationships above except Zuko and Mae.
I support Kataang, Sukka, Zukae, and Toph+Earthbending kid with mustasche