Long story short the 3rd entry in the Nanoha film series will be split into two movies. The first one is scheduled for a Spring 2017 premiere while the second one’s premiere date is unknown but the writers assure us that the wait after the first movie won’t be a long one.
In an interview in the same magazine, franchise creator Masaki Tsuzuki stated that the story will be completely new, and will take place three months after Magical Girl Lyrical Nanoha the Movie 2nd A’s, when Nanoha and the other characters are in the summer of their fifth grade. The events of the story begin when certain incidents begin occurring in Uminari City, as well as in the area around Tokyo, and so Nanoha and the others investigate. The story will feature other new characters besides Amitie and Kirie. The characters’ Barrier Jacket costume will also have a completely new design.