For me personally, the underwater worlds of Pandora will be amazing to see. Of course, we want Jake and Neytiri back but there's also gonna be Mo'at and Norm returning and a possible return for Grace, just hope they keep her role minimal, bringing back the dead isn't something I'm a big fan of. Quaritch and Trudy are both dead so they both get a big "HELL NO" from me. I really wish Tsu'tey didn't die, he was awesome and badass and it's a major bummer that we lost him but because he is dead, he shouldn't come back, same goes for Eytukan and again, it's sad he died thinking Jake was a traitor and never got to see him atone for his initial deception but I think that gives Eytukan a sense of tragedy and is something Jake himself has to live with, Neytiri loves him again, the clan worships him but he also has to live with the fact that Eytukan, the father of his wife and life partner, died despising him. I think it's time for some new major Na'vi characters to stand up and play key roles in the sequel along with a larger role for Mo'at, I'd really like to see a close mother/son relationship between her and Jake, that'd be wonderful to see. I'd also like the sequel to be a lot darker than the first. I'd say I don't wanna see another fall out between Neytiri and Jake but after he became Toruk Makto and they saved the Na'vi together, I don't think it's even possible for them to suffer another breakdown in their relationship, Jake has nothing to hide anymore and has proven himself to be a true Na'vi.