A few days ago, an event called Momocon was held and Steve Blum (voice of Amon), Sifu Kisu (martial arts master), and Sifu Rodriguez (consultant for Toph) were present for a question and answer session.
During the question and answer, fans were able to obtain new information on Book 2 of The Legend of Korra. What we now know is that a subset to Air Bending will be shown and the identity of Lin Beifong’s father will be revealed.
It’s interesting because these are two speculative topics I’ve already covered and voiced my opinion on. Many months ago, I speculated that the Duke could be Lin Beifong’s father. I also speculated the possibility of a subset to Air Bending and I ultimately rejected the likelihood of it being revealed to us.