Oh also one thing we talked about, not set in stone but it is the idea that each of the Princesses (and Prince) of Heart will be tied to a villain that represents one of the Seven Deadly Sins. For example, Mulan is a Princess of Heart, her nemesis is Shan Yu, the avatar of Wrath, and the Emperor holds Royal Authority in their world. 

This all depends on who ends up being Princesses of Heart.