Well this was mentioned only in Kamen Rider Official Website. ZAIA Enterprise CEO Rion Arkland is going to be Kamen Rider Zaia.
Either it's a ZAIA Enterprise developed Kamen Rider like Kamen Rider Thouser, or Azu will give Zero-One Driver to Rion just like how she did for Horobi and Esu in the TV Series. Maybe it will have a ZAIA inspired faceplate which will make his transform into Kamen Rider Zaia.
Since we are getting Kamen Rider MetsubouJinrai & Kamen Rider Zaia, may be also need Kamen Rider Hiden and Kamen Rider A.I.M.S. next to make the complete collection of Zero-One Organizations.
Thanks to the person who zoomed in on the scan released a couple a days, we get to see the complete title of Kiramager the Movie. It's called "Mashin Sentai Kiramager THE MOVIE: Bebop Dream".
As per Wikipedia, Bebop or bop is a style of jazz developed in the early to mid-1940s in the United States, which features compositions characterized by a fast tempo, complex chord progressions with rapid chord changes and numerous changes of key, instrumental virtuosity, and improvisation based on a combination of harmonic structure, the use of scales and occasional references to the melody.