Mileena will not return as a playable character in Mortal Kombat 11. Notably, she was one of the characters that ended up in the events of Mortal Kombat X's main story mode.
With Kitana's reveal and breakdown, these rumors appear to have been substantiated somewhat.
Recall for a moment when it was first announced that Jade would not be playable in Mortal Kombat X. It was revealed that Kitana would be able to use jade's staff and glaive attacks during her "Mournful" variation.
History appears to be repeating itself. Kitana access to "Half-Blood Stance." Mileena's iconic and unmistakable sai as it emits a purplish aura.
This stance allows Kitana to perform one of several of Mileena's special moves ̵
Kitana can be commanded to throw the sai at the opponent. Rather than throw it straight forward like Mileena, she throws it upwards instead.
Another option allows Kitana to perform a melee stab with the sai. After hitting with three thrown sai, this will cause massive damage thanks to the Crushing Blow.
Click image for animated version
So this raises a big question. Kitana Mileena's moves if Mileena what's in the game? More than likely, they did not.
Mileena does not want to be playable within the game's launch roster. Mortal Kombat 11's character select screen remaining.
However, considering that Shang Tsung has been announced as Mortal Kombat 11's first DLC character, all hope may not be lost. For the sake of the Mileena fans, here's hoping she returns as a DLC character – assuming she does not occupy one of the two remaining base roster slots.