To be perfectly honest, I would be absolutely shocked if the Wu Shi Academy wasn't already in the game. It's been established in the canon MK storyline that this is where Liu Kang and all the White Lotus Society train. I actually enjoyed that arena quite a bit...very unique, very 70's Martial Art movie. I hope it's in.
Otherwise, I'd also like to see the Acid Bath return. I know we already have the Deadpool as an acid fatality, but I always thought it was a crime against humanity that Deadly Alliance had an arena like that and it WASN'T a stage fatality. Don't know how they would pull it off on a 2D plane since the arena really was built to be a 3D fighting arena, but they could make it work. To differentiate it from the DeadPool, the stage fatality could incorporate the acid-vomiting statues. They vomite acid on the opponent who begins to melt, causing him/her to stagger around and ultimately fall off the side into the rest of the acid.