Which character do you hope to see them add? I think the current roster already covers a lot of bases in terms of styles so if they add one more I hope it's a unique "joke" character. Something like Dr. B, Gon or maybe Mokujin. Guests would be fine too, Kazuya was mentioned a lot and Harada kinda (?) teased him on Twitter when he posted a Lee screenshot with a shop from Yakuza in the background.
Also, this is a no Christie zone, we already got Eddy >:(