Don't give yourself too much hype, folks. Look at what Arcanir and Venus said.
A reveal could certainly happen, but that doesn't mean it will. I'm banking on a no, but if it happens, it's a nice surprise. As for whom if they did reveal, it's really likely for them to reveal Chorus Men/kids/whatever at an event like that, but seeing how it's mostly Japan only, I can't see it happening. Probably because it's a weekend and we just got an influx of info at E3 this month. Maybe a veteran or something, but a newcomer sounds like a pipe dream. The flier itself simply confirms there's more characters to come, if that wasn't obvious enough.
Another pointer is how the three third parties say "guest" next to their name. More of a signification that they'll be solely representing their series in my opinion...