the first persona game when it was localized was called Revelations: Persona, or Megami Ibunroku Persona.
the four character art images at the beginning of the trailer seem to depict modern high school versions of Marth, Caeda, Cain, and Abel. Tiki is prominently featured as well between posters bearing her name and the scene where you straight up see her. she has a different design from the poster (More modernized) and the cutscene where you see her (Standing in front of the altar wearing something closer to a Jpop Idol costume version of her actual FE1 appearance)
likewise, we see our hero with more vibrantly blue hair, a rapier, and a cape with blue on the outside and red on the inside... kinda like Marth. the female protagonist also gets blue-ish hair in her transformed state and rides aorund on some sort of flying hooved quadruped and wields a polearm... much like Caeda, the first Pegasus Knight. we also see Red Dude on a motorcycle, which is... the closest modern day equivalent you'd get ot a cavalier. this is why I believe this is Cain and his counterpart is Abel.
I'm guessing that we're dealing with some sort of modern urban japan setting that at the Dark Hour/TV Land/Whenever the Fire Emblem Hashtag is used on Japanese twitter that people who paralell characters from Fire Emblem become their fantasy hero counterpart, and that we're going to see some sort of glammed out weird tarrot card monster version of Medeus.