Ace will be added into the game as a playable character in the future.
Though his moveset would be tweeked so that some of his attacks wouldn't be too similar to the moves he copied from Street Fighter characters, for copyright reasons.Any of the other Fighting Layer cast?
Well, considering that (besides Allen and Blair, which are already in the game) there are some character themes when using the Extra soundtrack option, its probably safe to assume that they might come back in some form, unless probably after the original EX cast (and Terry) are out. The title 'Fighting Ex Layer' can't be just without them.