I don't believe this leak. Not saying that some of this might happen, but it's just weird.
I feel like he listed way to many premier skins to the point where it's unbelievable. There were weird typos in there too, like saying "Dr. Freeze" instead of "Mr. Freeze"
If this was someone who works on the game daily, I'm sure he would know the correct names. I also doubt that there are 2 "missing" characters from the leak, and even if there are some, I doubt that it will conveniently be Starfire and Red Hood -- the 2 most requested characters right now.
The leaker we know that is legit has mentioned nothing about these characters and skins, and we know he is still seeing stuff because he just leaked Black Manta as DLC not long ago. Because of that, I honestly feel like Black Manta will be the first DLC character (or at least one of the first). If that's the case though, and they are already designing him, wouldn't this leaker see his designs if he was the character that's getting the most attention currently?
Sub-Zero and Vixen are pretty safe bets too, by the way. I also like how he said "things can change". Like, nah. They already have their DLC planned, just like KP1 in MKX. He just said that to cover himself if it doesn't happen.