I think it's going to be a character in some form of Raidou, whether it's brother, son, uncle close friend ect. He'll be the DOA rep of Akuma. Also seeing the DOA 1 level in, sort of hints at a DOA1 character or some what similar. Does anyone recall a male character from doa scrapped?
The only male characters included in the series but not playable in DoA5U are Raidou, Bankotsubo, Genra and Shiden.
Considering that the last 2 are characters playable only in the recent Dimensions, and how I doubt that they created a replacement for Bankotsubo only for including him later, the only one remained is Raidou.
By the way there are effectively 2 characters half-scrapped:
1) Kelly: This was a character appeared only in a demo showing a prototype version of DoA for promotional purposes: this character used Muai Thai (and had a facial appearence pretty similar to Jann Lee even if the Kung Fu pratictioner was already planned like it's possible to see in this picture). It's useless to say that he ended to mutate in Zack for the final version of the game
2) Kamui: Well, this is neither a scrapped character, rather a scrapped concept: originally DoA had to include an original ninja guy with this name (not sure if his name was written with the Kanjii used for Naruto's manga ( 神威= ) in that case it would mean "Authority of the Gods"). However a member of TN suggested to Itagaki to not use a generic ninja but rather the same Ryu Hayabusa of the original NG series owned by Tecmo... and everyone know how the story ended.