At the end of the day, even if Tanya was confirmed, which I have never heard or read anywhere, only speculation that she is in the game, they still have liberty to change their minds whenever they want. Both characters have dark skin, so it could be either of them, and don't decide who it is by their hair either, because Kitana's hair has grown alot since MK2, so really to say "Tanya has longer hair than Jade would" is absurd.

Saying that this character in green doesn't look like Jade is ridiculous. Jade was just a pallette swap of Kitana. Plus she wore a mask. How can we truly say what she looks like??

This character could be either Jade or Tanya, and they could even change the name and story last minute because both characters are quite similar in terms of looks and are both Edenian, serving quite similar roles. Maybe we should just not speculate and wait until we know, because I know for sure that it's going to drive me mad thinking about it!