Ok, first off let me clarify one thing: I am not a leaker, the following are just my speculations and your speculations are good as mine.

Again, this is not a leak, I am in no way tied to Ed Boon or any other member of his team. The following are not even rumors, just my theories, made out of passion and deep MK lore knowledge.


- The Story of MK 11

Using the ending of MK(2011) as a "mold" I'd say that what was hinted in the post credit scene in MK X story mode is going to happen most likely.
MK9 ended teasing us Shinnok, Quan Chi and the revenants. Exactly what we got in MK X.
So, I suggest that, before speculating on Onaga, Blaze, Daegon and Taven, we should talk about Dark Emperor Liu Kang and Dark Empress Catwoman, I mean, Kitana.
It is pretty obvious that this royal couple is the new Deadly Alliance.
If, and that's a huge If, the original timeline is going to be used as a mold/stamp, then we already know that almost all of the Heroes will die. The few surviving heroes will be new faces, old, returning characters (Fujin?Sareena?Jade?), returning from MK X (Cassie?Takeda?) and the iconic duo of Scorpion and Sub-Zero.

- There are several plot points that are hinted in the story mode and the arcade endings:

- Shang Tsung's redemption is hinted since two games, in his ending in MK9 and in Bo' Rai Cho's ending from MK X, where Shang doesn't appear, but it is made clear that Outworld needs warriors.
This leads me into the next point:

- There will be a new Tournament, this time Earthrealm will be the bad guys, and Outworld the good guys.
This will be roughly the first half of story mode. Dark Raiden will lead a force of invasion against Kotal and his minions. However, Earth heroes won't like how Raiden behaves, so there will be some inner feuds. I can predict a small group of heroes siding with Raiden. Sonya, because she wants to kill criminals. Jacqui, maybe to avenge Jax's death (more on this later), Kano and the Black Dragon in exchange of protection, Scorpion due to his blood thirst. Frost could side with Raiden just to gain help in reaching Lin Kuei's leadership and prove herself even without the approval of Kuai Liang.

- On the other side Fujin will be the leader of the "ethical" heroes alongside Kung Jin who wants to honor his shaolin ideals and beliefs (and save Kung Lao), Johnny Cage because he acts like a superhero, Cassie because she doesn't share Jacqui (if Jax really dies, remember that's just my speculation) and Sonya's thirst for revenge, Kenshi, because he only wants to kill Daegon and the Red Dragons, but is a more moderate guy with the other baddies. And Sub-Zero of course, who wants to save his brother and Frost.
An interesting scenario is Takeda's one if my theory is correct: he struggles to pick a side. His master, mentor and father figure is hellbent on revenge, his biological father and "best friend" (quoting Kung Jin's words in Outworld prisons) sides with Fujin.

- Bo' Rai Cho will train the Outworld finest warriors and will introduce a couple of new ones on his own, one of them is Li Mei. A possessed Jade is a possibility. Shang Tsung turned good or at least anti-hero is another possibility. Finally Reptile, a new Mileena's clone, Baraka if he comes back or a new Tarkata, Erron and Ferra/Torr will be A-listers and maybe one or more of them will be playable in the story mode and score a few victories. Kotal Kahn of course is part of this Faction and will force a captured Tanya to join his ranks as well. Rain too if he survives, however Tanya's ending was clear on this point.

- Despite Bo' Rai Cho's help, I can see Earth winning. But this victory will lead us to catastrophic outcome. With the defeat/death of Kotal Kahn Outworld will be without a protector/ruler. Raiden will unwillingly reawake Onaga (Outworld's original protector and ruler) and create a new, more dangerous menace.

- Raiden and Fujin (with their respective sides) will form a truce and will seek the aid of new allies coming from other Realms, like Seido, Chaosrealm, Netherrealm, Vaeternus(if it is free of Outworld) and Dreamrealm.

- Liu Kang will give them the middle finger of course, and maybe will align himself alongside the Revenants with Onaga (a reminder of the original timeline in which the heroes killed by the Deadly Alliance were resurrected as Onaga's bodyguards).
Hotaru and Havik will make a cameo, will be hinted for MK12, but won't side with anyone. Maybe will wait the outcome of the battle and help the winner. Vaeternus and Dreamrealm are wild cards, the Dream Lady and possessed Jade will follow their own agenda and will pick a side accordingly.

- Onaga and his allies (mostly new characters and the few surviving Outworld Mortal Kombatants)will destroy everything, but somewhat, somehow Onaga will be defeated. But Fujin and Raiden will resume their war, exactly like Batman and Superman did in Injustice 2 after defeating Brainiac. I can see a "pick your path" option slightly before the end.

- Liu Kang and Kitana will strike a weakened Raiden and put him in the Netherrealm side by side with Shinnok. The Revenants will stay Revenants, maybe with the only exception of Kung Lao, healed/purged by Kung Jin.

- Taven and Daegon hinted as a post credit scene. A Raiden and Shinnok alliance in Netherrealm is another possibility (already hinted in MK: Armageddon bios and Konquest Mode).

- Plots hanging from MKX:

- Jax's death by Erron Black/Kano, hinted in Sonya and Jax endings.
In particular, Sonya dreams about Kano forcing her to chose who to save between Jax and Cassie. Death in a dream. This makes me think of the Dream Lady. If this will turn to be true, then the Dream Lady is not part of the Forces of Good and for some reason she will help the Black Dragon or the bad guys in general. This is the most interesting scenario imo. Nothing against Erron Black, but I can see him being tormented by his Earthrealm origins and his desire to help Kotal and BRC in the Tournament. Kano killing Jax would fuel his rivality with Sonya and would give Jacqui a more dark and obscure, vengeful role. No longer the good girl, she leaves the military just to hunt down Kano, maybe will ask help to Takeda, but he will refuse because he doesn't believe in vengeance and violence. This will mark the end of their relationship and Jacqui will join the Red Dragon. This gives her a lot of depth and interesting future scenarios, especially in the final showdown between Kenshi and Takeda against Daegon and his clan.

- Jade, Noob Saibot and Shang Tsung will come back most likely.
I already spent too much words on Shang and Jade roles (redemption or presumed redemption for him, henchwoman/enforcer of the Dreamlady for her).
Noob Saibot, on the other hand, is too much of a requested character to be ignored, but at the same time I cannot see any real story role for him. Maybe his supposed alliance with Havik, as hinted in his ending from MK9, could be a future plot twist. Or maybe Frost will look for his help to dethrone Kuai Liang from Lin Kuei's leadership. Personally, I see him as a generic villain in Story Mode, but he won't have his own chapter.

-Other characters I can see coming back: Dreamlady, Sareena, Fujin, Frost, Li Mei and Onaga.
The Dream Lady has been hinted since 2011 with Jade's ending. Usually hanging plot points are left "hanged" for a game or two. After that this line is crossed, the story is resumed or forgotten, and would be a shame for its potential. Considering how Jade was the only character not appearing in Revenant form, the only logical explanation is that this Dreamrealm Lady is behind her resurrection.
Sareena, Frost and Fujin are highly requested, they even had a fight scene in MK X's Story Mode and were DLC candidates. However Frost and Sareena are not popular enough and the starting roster is limited to 28-30. Fujin, on the other hand, has the same role of Batman in Injustice 2 and is likely to replace Raiden as Earth protector. He has high chances to be back, but again, he isn't that popular outside of the core fandom.
Li Mei is BRC's pupil, I can see her joining Kotal in defense of Outworld, mirroring her role in the original timeline. Onaga is needed as a badass/monster like final boss. If not Onaga, a new boss. Dreamlady is interesting, but I don't want to see the entire story revolving around her and Jade. Frost is on her personal quest to gain power: she will face Sub-Zero, gets her ass killed so she seeks Triborg and his Tekunin for help. Maybe she will accept to be turned into a Cyborg. Or will ask Noob.

-Tremor, Kano and his son will be back, but again, I cannot see them as anything different than a generic villain with no chapter in Story Mode. However, Kano's son could have some chance if he becomes a good guy. In Kano's ending in MK X we learn that his son is trained through violence and torture. This could lead Kano's son to two possible outcome: he will be exactly like his father, or he could hate his father and just wanting to be a good person. Perhaps he will join forces with Cassie and will be something more than an "ally". A love story between Cassie and Kano's son is a scenario plenty of possibilities and plot twists. I would love to see Sonya's and Johnny's reaction to the relationship between Cassie and Son of Kano. It could be both hilarious and dramatic at the same time.

- Liu and Kitana will have an important role: they are King and Queen now, it would be credible for them to learn and show some diplomacy. While Liu Kang was always shown as hot tempered, especially in MK9, he has Kitana and maybe Sindel at his side, so he will wait for Raiden's fall from grace and defeat, in order to give him the coup de grace and sealing him off in the Netherrealm like Shinnok. The other Revenants will help Liu and Kitana against the rest of Raiden's faction.

- Scorpion and Sub-Zero will try to get along and put their differencies aside, but the fandom is more keen on keeping them as enemies, rather than allies. I see them starting as allies, but then taking different routes: Scorpion will side with Dark Raiden, seeking retribution and blood, Sub-Zero on the other hand wants to show that the Lin Kuei is a force of good. He ignores Noob's whereabouts, but wants to save him. So the most logical choice for him would be siding with Fujin.