While I think it’s plausible for the remaining unnanounced worlds to be potentially candidates of the new princesses worlds, one thing people is forgetting is the idea of how a pure heart should be. If you think on the KH1 princesses most of them are good natured girls with wishes and only good intentions, even Alice behaves like that. If we go by that nature then Rapunzel, Anna and Elsa are true candidates to the job, Kairi was confirmed as the only returning one, so that leaves 3. If we consider the rest of the girls in the announced worlds I would say Elizabeth doesn’t have a pure heart, specially in the third pirates film from where this world is based of. Boo as a child could be but due to her young age I am not sure it could work. Megara could be but it depends on if she appears at all since her role seemed closed in KHII. As for Go Go and Honey Lemon it’s a 50/50 as of now, Go Go I wouldn’t think so, Honey does behave mature and lighthearted but something tells me she doesn’t belong to the group. So from this point which female Disney characters have those princess traits: I would say Tiana, always working hard and taking the right way while sacrificing herself for faith in her dream. Pocahontas, love for every living thing and nature, a girl who loves her people, nothing calls light like that. Merida, her brave and adventurous spirit would make her a good candidate IMO but like Elsa she might be followed by a bit of darkness seeking to taunt her heart like Elsa. Moana as someone mentioned would fit but because of the “no movies after BH6” thing I don’t think so. Kida is a great option as well but because of her rough nature it makes me doubt. Also we have the chance of another original but as this is the final game of this ark it could be troublesome to the lore IMO.