With the release of the new MKX comic (issue #4) a lot of questions have been given answers, and the story has become much clearer.
I'll start with discussing Kotal Kahn, and D'vora's first appearances in the comic. Here we see both of them being interrogated by none other than Sonya Blade, and with them there's another character that we have yet to be introduced to, his name is "Erron Black"
Kotal Kahn had come to Earthrealm to vanquish the Red Dragon clan, since he's saying that Mileena had allied herself with them to get the throne for herself. Apparently there was a civil war going on in Outworld between Kotal Kahn and Mileena.
He says that if Mileena does become the ruler of Outworld, then he will suffer a terrible fate, and so would Earthrealm, because of that they need to form an alliance.
To think this through, we know that the Red Dragon was founded by Daegon, and that they are allied with Shinnok, so for Mileena to be allied with them, that means she's allied with the people that aim to take over outworld and earthrealm, so does that mean that they're planning to backstab Mileena? Also, does that mean Kotal Kahn's going to fight Shinnok and the Netherrealm since he's actually already waged a war on the Red Dragon?
But it doesn't really stop there, This Erron Black doesn't stray too far from being a new character, he's mysterious. which gives him a good enough theme for it, and he has a good model, but we really have no idea on who he is. This could be how Netherrealm want it to be, Hell maybe the whole next issue is going to be about him, or maybe he's getting released this week.
Also we get to see a somewhat retro character make her way back, sure enough Frost isn't really what i'd consider a fan favorite, and her storyline doesn't really fall in place since all we know is that she's part of the Lin Kuei and that she was planning to overthrow Sub Zero and become the grandmaster.
Generally all we know about Frost is that she sparked Sub Zero's interest when he saw that she was a formidable warrior, and he thereafter made her his protegee, later on Sub Zero was asked to help Raiden, and in their journey to outworld Frost betrayed him and stripped him of his Medallion. Upon wearing it, Frost died. She was then buried. Later on in MK Deception she awakes, and after killing many Lin Kuei warriors, she is frozen and sealed off behind an ice wall in the Lin Kuei Temple.
To think it through the only way Frost could've made it out and into an MMA ring, is if she escaped her first tomb and ran off, but it doesnt really make sense since she would have no way to return to Earthrealm from Outworld.
What we can say for sure is that Mileena has somewhat of a 99% chance of returning, since
A) it wouldn't make sense to have Kitana return, and not Mileena, since it was said before that Mileena and Kitana are like Sub Zero and Scorpion, and Liu Kang and Kung Lao.
B) She was accidentally announced in a leaked video commercial in MKX (similar to the doomsday Injustice incident) (you can read about that here)
C) She was waging a civil war against Kotal Kahn and she has a very major part in the storyline
D) She has somewhat of a perfect attendance record when it comes to Mortal Kombat titles and movies, only missing out on about 2 or 3 titles and being seen in about 11
E) there really is nothing to suggest that she won't come back
When it comes to Frost, there's actually less convincing evidence, but what we do know is that:
A) she was seen in the background in MK9 fighting Daegon (as well as in Raiden's visions)
B) She was seen in Issue #4 of the MKX comic
But she hasn't really been in most Mortal Kombat titles, and really her story does not fall into place at all.
Now about Earthrealm siding with Outworld, that does actually seem like a very probable outcome, since both realms are weakened, and they cant really overcome the whole Netherrealm force by themselves. Logically they would have to team up for the greater good of surviving, even if they've fought vigorously in the past. But keep in mind, they only fought because Shao Kahn intended to join the two realms, but he is long gone.
What do you think? Would you like to see Frost return? And what do you think's going to happen between the two realms.