We are still talking about theatrical production, yes? Book 2 won't be split. Maybe Book 3 but only if Book 2 does well. They might even skip Book 1 altogether. Don't get me wrong -- a 5-movie reboot sounds lovely but a studio rather greenlit other projects with less financial commitments and bigger bang for the back.
For the same reason, a Zuko prequel movie is also not gonna happen. It's a recurring BS posted on VCpost for quite some time. Maybe a TV movie but definitely not a tentpole one. However, it can be a subplot in a movie or two, just like "what really happened to Zuko's mom".
@SorcererSupreme21 I suggest you close out this thread and start out a new one, because we are hitting Wikia's 500-comment limit on threads. I have goodies to post but I have been very busy with work lately. Oh, I am fancasting Kenneth Choi as Uncle Airoh. He's an American actor with comedic talents, though he might need a stunt double for the action scenes.