I was looking through recent blog posts and I saw one with a similar title to mine, except that one was only 1 sentence long and it simply asked users what their predictions were. Well, rather than writing this in a comment I decided to write them here:

Main Plot Edit

1. Since Book 2 is still technically in the first season, it would make sense to believe that the two plots are closely related.
2. I believe the Equalists will still be around (if not all, some). How likely is it that they'd stop hating benders after Amon died?
3. Hiroshi Sato will be the Equalists' new leader.
4. Team Avatar will visit the Fire Nation and accouter the Fire Lord (Zuko's daughter) and Zuko
5. Zuko's wife will be Suki. (Read The Promise, Part 2. It is possible)
6. It will be revealed that Sokka ended up with Toph. (Again, read The Promise, Part 2.)
7. Lieutenant will become an important ally.
8. Asami will ultimately be the one to bring down her father.
9. We'll see a Patik-esque character help Korra out with Avatar State.
10. Korra will speak with Roku, Kyoshi, and Kuruk.

Shipping Edit

1. Asami will be so focused on her dad, she won't worry about Mako.
2. Another girl we don't know yet will meet Bolin.
3. Lin and Tenzin will grow closer together (I'm calling for Pema's death in Book 4, seriously)
4. Korra and Mako will go through difficulties, but unfortunately, everything will be super perfect by the end of the book just like Book 1.

Other Things Edit

1. Katara will die.
2. Korra will master Airbending (kinda obvious)
3. Tenzin will become the Council's chairman