I wanted for Rinne to became an earth maiden and join their circle in a few years. I liked her character the most. It left me dissatisfied that we could no see it with such an open ending.
There are also some horrible implications about the past. My theory is for the past 100 years, that's at least 4 generations of Shrine Maidens this island is ruining their lives. First of them end up sacrificing (committing suicide for no reason). Second, suck it up and close herself up for the good of island, disregarding anything else. The last one leaves it all behind to escape and regret it all their life. We can see it in last generation. Mother of Shizuku is a case 2, mother of Nagi is the 3. case. The first case didn't leave any descendant obviously. Such a terrible tradition.
Even the dragon god itself said that this shit is repeating itself over and over.