Well I don't know, it's just a random supposition. I think it's time to announce their second newcomer, one month before the release, but maybe it's still a bit early.
Helena VS Gen Fu and then Helena VS Mila would make sense in a trailer, especially if Helena and Mila are together on the screen. Well, I know it's not definitive, but I have the feeling "tag partners"/"linked characters" are not only top/bottom on that screen, but also left/right (look at Helena/Kokoro, Tina/Lisa).
That would mean Mila has something to do with Helena, and since they generally (but not always) revealed characters that were linked (Zack/Lei Fang in the circus, because of Story Mode, Brad/Eliot who are friends, Bayman/Christie, who are sexy rivals, Christie/Rig with that mysterious dialogue), I think officially revealing Helena's render and Mila (and probably Gen Fu) in Famitsu would make sense.
And Pai is still a mystery. They probably will keep her for TGS.
But that's just a supposition, again. Maybe we won't have anything tomorrow..