Not even speculation. Just suggestions. Repost any that anyone posts which you like and feel free to offer your own.

Since we know that Shinnok is going to be a villain in this (and will most likely die at the end of the game alongside Quan Chi), I'm hoping that we get to see the effects of a power vacuum in the Neatherrealm in the next game in the same way that we see how Outworld reacts to the death of Shao Kahn.

IMO, MK11 should add these fighters to the roster to represent the forces fighting for Shinnok's throne.

Noob, Reiko, Sareena and Ashrah.

Noob wants to continue Shinnok's work, assume the power of a god and then rule the Neatherrealm as his successor. He's currently the most powerful leader.

Reiko has betrayed Noob and has split the Brotherhood of Shadow. As a new Elder God, he will unite Outworld with the Neathrrealm. His plan is to use Ermac to fuse the soul of Shao Kahn to him so he may have all of Sheo Kahn's power which will enable him to easily crush his enemies and seize the power of an Elder God for himself.

Sareena would redeem the Neatherrealm as Elder Goddess and allies herself with the Lin Kuei.

Ashrah would be opposed to all three warring leaders of the Brotherhood of Shadow. Her goal is to redeem herself by slaughtering all of the undead within the Neatherrealm and bring the departed souls from death into oblivion. As Elder Goddess, she would remove the entire realm from existence so she would be known as the one who purified herself and her realm alike. She believes she's fighting a holy war but the truth is that she's nothing more than a crazed fanatic.

I'd also bring back Smoke and Sektor back from MK9. Then I'd reintroduce some of the 3D characters. Namely Fujin, Bo Rai Cho, Li Mei and Nitara.