It may not be the right thing to do however I feel the need to point it out. Something suspicious was said in the Lady gameplay stream by capcom unity (the one in News and Updates). If you watch the video and go up to the 25:40 mark.. You'll hear the sidelines guy say"but there are 3 new characters dude", and then grega says "four" as if correcting him. Immediately afterwards you can hear jumbled conversation followed by WHISPERING. Note: only three new characters have been revealed. Vergil, Trish, Lady. First ign and now capcom unity themselves. I believe Lucia is the most likely newcomer and the one that can bring more variety than Credo or Sparda.
I went back to the video, and I'm not hearing it, sounded more like "or" to me then a "four".
Not that I'd mind more characters but I won't get my hopes up. And if there is another one, they'll give us Lucia since they already got a template for her.
Sparda is no possibility since we already got the costumes for that, same with Nelo Angelo.
Credo is a possibility, still his DT would have to be reduced in size since he is huge compared to the other characters, besides that I think it would be lazy to have him playable, that would be pure recylcling.
Other then that, there are no characters from the franchise that could be made playable in my opinion. They could give us a completely new character or a character from another series (Sengoku Basara would be a possible pick, due to the stageplay) but that would come out of left....