Ignoring any leaks, and including the Konfirmation of Shang Tsung, my 5 HOPES for DLC are:
Fujin: Not a huge fanboy of him, but he deserves to be playable. I always loved the concept of wind powers. And we could use a character with as minimal weapon usage as possible.
Takeda: The Koolest Kombat Kid, i love the potential for gear and ability customisation he has. Although i love Kenshi, his son can fulfill a playstyle similar to him if necessary.
Havik: A super interesting character design, who i would reckon could have great dialogue with many of the characters in this game. His body contorting moves with modern graphics would be difficult to animate, but amazing to see.
Sheeva: Shokan representation dammit! She was the first ever playable shokan, and they did her some dirt in Mk9. Bring her back, make her viable and make her interesting! I always wanted her to fire 4 small projectiles quickly as opposed to 1 huge projectile. Give me my rapid fire shokannon!
Sareena: Amazing backstory, and with Quan Chi being dead her presence could make sense. Her abilities in kombat have always been fairly vague, i'd like to see them flesh her out somewhat.