I'd just like to speculate that this game will be all about reincarnation or at east have this theme. This is nigh confirmed by, as in that video we see the starlets top song "Reincarnation". For those that don't know, the idea of reincarnation and transformatio (Another theme heavily shown in the trailer) is pretty much present in he recent SMT and persona games. SMT: DDS has this constant theme of hindu reincarnation where the characters struggle to break away from Samsara, the cycle of reincarnation to reach nirvana with their transformed selves, their Atmas. In SMT nocturne, the entire world is reincarnated as a wasteland and you with it as "The Demifiend". SMT IV you go from being a casualry slummer to a samurai, a new incarnation of yourself. In Persona each and every persona user grows and changes, represented in the transformation of their Personas. Hell, the very game mechanics themselves reflect this, the idea that you fuse personas and demons to get stronger reincarnations of them.
That said, i think the story will revolve around modern reincarnations of Fire Emblem characters and their classes.