Mortal Kombat: New secrets Bosses

Thanks to the recent video interview of Ed Boon creator of Mortal Kombat series, you can see that during the tower challenges there are 4 slots of characters above Goro that are not being showned, and these characters are secret bosses that the game may have, which one do you think are: Kintaro, Motaro, Shao Kahn, Shang Tsung or Quan Chi?