That's a pretty thrilling perspective. With everything at place, this arc will be more likely answer the questions we have for several years regarding Ai. But since Akasaka, I believe, never mentioned that this will be the last arc, despite with how things are going with the movie is a perfect way to end the series, there will be more likely a supernatural twist, given that there are some kind of supernatural beings involved. Once Aqua faced his father, and he either do the deed or not, what's next? Ruby didn't have any closure with what happened to the doctor and her mother. Will that be answered after these events unfolded? Damn... I am reading too much on this series.
:V