Extremely wishful thinking here but maybe they would have something like they did during the s2-s3 hiatus where they had those special little clips online featuring the four Avatars of Christmas' Past when Aang was unconscious.
*looks around* What, no? You say they're past that and it'll just be a bunch of speculation from here on out? Oh, ok then. So, not even an extension off the third movie for Zuko's mother? Maybe? Wait, really you think so?! Oh, you were just joking? No, no, I'm okay. I'm not even a little upset. Nope, not at all. No-sir-ree bob, not me. *sulks*