After watching the trailer dozens of times, and reading the comics again.. I came up with a theory..

"Remember MK9 where they split the story in 3 parts where they retold the first 3 MK Games?

I have a feeling it's going to be the same in MKX.

In the comics, we see the events as it happens after the Netherealm Invasion.. I believe what we see in the comics is technically the middle part of the MKX story. Spanning over 25 years, the end of the 25 years is probably what we are seeing in the trailer. The battle between Kotal Kahn & Mileena.

Everything in the comics is a build-up to the last 'chapter' in MK's story mode. Where the Special Forces will team up with Kotal to take down Mileena and her rebels.

So, what's the middle 'chapter' about? This is the part I'm not too sure about. I believe this is the part about the Kamidogu. I can't link the Kamidogu to either the Mileena-Kotal war and it's happening after the Netherealm Invasion. So, the Kamidogu story could be in the middle.

So who or what is this demon Raiden warning about in the comics, regarding the Kamidogu. It could be someone else we haven't seen. I'm inclined to think Kotal Kahn. It would be crazy to think the current Outworld Emperor not being given a Boss role.

My theory.. Kotal is posessed by the demon, after using Blood Magic. He's defeated, releasing the demon. But since the reason why he resorted to using the Kamidogu was Mileena herself.. so Mileena becomes the Final Boss.

So, the first 'chapter' will be the Netherealm Invasion with several of the Earthrealm fighters in that battle. Everyone's waiting for the Quan Chi & Shinnok-led Invasion so I don't think they will leave that out.

Chapter 1: Netherealm Invasion (Boss: Shinnok)
Chapter 2: Kamidogu (Boss: Possessed Kotal Kahn)
Chapter 3: Kotal Kahn-Mileena War (Boss: Mileena)"

Full story at my blog: http://www.drjengo.com/2015/03/mortal-kombat-x-story-trailer.html