Aang is DEAD. New avatar yo. That mean he's BEEN dead, for at least 16 years. since this chick is 16 or whatever. Instead we get his son.
Of course Mai and zuko will have a child, someone's got to take over the fire nation.
Bermy or whatever his name was could still be alive by the way. earthbenders live longer than other races, for what reason I'm not sure, maybe they can bend the toxins out their body. This would be typical of their humor. This also means that Toph is still probably alive, doin stuff. She's probably found herself some wussy to boss around and Mary. Yeah, this would also be typical of their story telling, as it would be a reference to toph saying Do you think Friendship's can last more than a lifetime" or whatever she said.
We'll probably get caught up on all the major charecters, and see the good taht Aang and Zukko did for the world. My guess is that the sought to bring the 4 nations closer, and to help make those who couldn't bend less dependent, however this turns into anti-bender relationtions as we already know is part of the plot, and its not time for the new Avatar Korra to unite past values and future ambitions.