There is no resemblance at all, theres no way she could be related to Midna. Although there may be some connection between Hyrule and the Twilight realm left intact I don't think we will be traveling that way for a long long time. Midna said her goodbyes, and Link has moved on. If she were to come back into his life it would complicate things too much, splitting his allegiance between the kingdom of Twilight and the Kingdom of Hyrule. In TP the two kingdoms fates were intertwined so it was ok for Link to help Midna out, but he is a protector of Hyrule and throwing princesses at him from other kingdoms repeatedly would make it hard to actually get one of them, no I think besides Princess Zelda, Link should stay away from the other Princesses, I'm hoping the mysterious girl is a sage or from a new tribe, also I hope that Link travels away from Hyrule to a land without a Kingdom.