Regardless of which Princesses show up, it is bound to be interesting.
Maybe Tigerlily from 'Peter Pan' will appear? She's technically a princess. Although, it's highly unlikely since she didn't talk in the movie...
I think Pocahontas could appear to support Sofia in an issue involving Lani, since they are similar. This hypothetical episode could be a continuation of Lani's debut episode; e.g. she's visiting her friend and ends up experiencing a culture shock then Pocahontas shows up to comfort her & Sofia.
I think Pocahontas may appear, but not Anna and Elsa. They're not official, and Olaf covered their spot.
I actually Think they will appear just because they're official disney princess & she has the power to summons so yeah just my opinion
Anna and Elsa actually are not official.
Remember this it's not about box office success it's about how well it's franchise is selling, same for Moana because the 3 have not joined yet.
No one never knows, Disney probably will add them to the lineup because they've already confirmed that Anna Elsa and Moana are going to be in Wreck it Ralph Breaks the internet being scene along with the princesses so it may hint that they'll probably join eventualLy soon