Around a maximum of 10 Trilogy characters that should/will most likely return...
* MK TRILOGY CHARACTERS:
The ones who NEED to return...
Scorpion
Sub-Zero
Raiden
Kitana
Liu Kang
JADE
Noob Saibot
Triborg (We need to know more about his origins.)
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And then ANY or NONE of the following...
Kung Lao (He's been in too many MK games and would most likely be DLC for fans to buy.)
Nightwolf
Sindel
Reptile
Khameleon
Shang Tsung
Skarlet (I know she's in MK9 but what the heck lol.)
Shao Kahn
Rain
Smoke (As Noob-Smoke would be nice.)
Kabal
Jax
Ermac
Goro
Motaro
Kintaro
Sektor
Cyrax
Stryker
Sheeva
Considering Mileena, Baraka, Kano, Sonya, and Johnny will not be playable if the leak was true. Though these characters can be used as DLC for fans to buy.
* MK Mythologies to MK Armageddon Characters:
Those who NEED to return...
NITARA (At least as a temporary replacement for Mileena in this game).
Tanya
Li Mei
Sareena
Kenshi
Taven
Daegon
ONAGA
Tremor
Hotaru
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Then ANY or NONE of the following...
Kira
Dairou
Darrius
Blaze
Reiko
Havik
Shujinko
Frost
Drahmin
Moloch
Quan Chi
Kia
Jataaka
Jarek
Tasia
Ashrah
Hsu Hao
NEVER have Meat, Bo Rai Cho, and Mokap playable again. I'd love them to be victim's of practice mode though. Shinnok should sit this game out too unless this game will be like MK Trilogy, MK Armageddon, or the Tekken Tag Series.
* MKX and New Characters:
Cassie
Kung Jin
Takeda
D'Vorah
Jacqui Briggs
Kano's Son
Salina (A rumored character who is a dream goddess and possibly the woman in Jade's MK9 ending. She can be the same character as Jade.)
Erron Black
Kotal Kahn
I didn't put Ferra and Torr here since they were rumored not to return in the leak.
Now let me put together the characters who NEED to be in the game (about 26-27 characters)...
1. Scorpion
2. Sub-Zero
3. Raiden
4. Kitana
5. Liu Kang
6. JADE (I definitely need to play as her again and know about her whereabouts. She can be 1 character with Salina.)
7. Noob Saibot (I need to know about his whereabouts. Maybe he can return as Noob-Smoke again.)
8. Triborg (We need to know his origins.)
9. NITARA (At least as a temporary replacement for Mileena in this game).
10. Tanya
11. Li Mei
12. Sareena
13. Kenshi
14. Taven
15. Daegon (To represent the Red Dragon.)
16. ONAGA (A very powerful boss character that needs to return. A sub-boss that can replace Goro would be him if he will not be the final boss.)
17. Tremor
18. Hotaru (Representing the Orderrealm.)
19. Cassie
20. Kung Jin
21. Takeda
22. D'Vorah
23. Jacqui Briggs
24. Kano's Son (A new replacement for Kano to represent the Black Dragon.)
25. Salina (A rumored character who is a dream goddess and possibly the woman in Jade's MK9 ending. She can be 1 character with Jade.)
26. Erron Black
27. Kotal Kahn
It'd be nice to have the following to be secret characters or DLC...
* Jade and/or Salina
* Noob Saibot
* Onaga
* Raiden
After the 27 characters (or 26 characters if Jade and Salina will be one character) are in, the roster can add and multiply from there.