Picture is worth a thousand words, or I suppose, two thousand words.

Loc test photos of SSFIV arcade, notice the two empty spots on either side of the roster.

Speculation? Hopefully not Yun nor Yang. Yun is redundant thanks to Rufus and his dive-kicking shenanigans, and all of the worthwhile nostalgic characters are already accounted for. If an older character is brought back expect a complete mechanical revamp a la Cody, or (hopefully) two entirely brand new cast members.

Thanks to my friend Dave who found this on versuscity.net!