Now, it was stated earlier on that the boss for MKD would be the Dragon King. But why did Boon and Co later state later that the Dragon King was "our Motaro, our Goro"? That would make him a sub-boss. So who would then be the boss? Liu Kang!
After the Deadly Alliance tournament, we know that The Dragon King and his army were successfully revived. Hence, a new threat was born, but this threat was not strong enough. Not yet. They needed a leader, a powerful adversary to help the army conquer the realms.
Now let me ask you a simple question. If you wanted to take over a realm, who would be the most powerful threat to you? The leader of your enemy, right? And who has been the reigning Mortal Kombat champion? That's right, Liu Kang! (we assume for the time being that Shao Kahn is dead).
Assuming that the MKDA storyline remains, that would mean Liu Kang died, but his soul was consumed by Shang Tsung. This would mean that his soul (spirit) would be separate from his body (zombie). But at the end of MKDA, Liu Kang's spirit did return, as Kano (I pray this didn't happen), and the first thing he does is escape Shang Tsung's palace and go into hiding.
That leaves Quan Chi as the sole survivor of the Deadly Alliance. With that, The Dragon King and Quan Chi form an alliance. (They did release a screenshot of Quan Chi, so let's assume he's in the game).
Now, John Vogel said "A new evil power will appear. It will lead the world to a total annihilation. During the years the Elder Gods have expected this and they have prepared for it. With the aid of the chosen one they will try to protect all that exist...."
From MKDA, we know that Quan Chi is able to revive dead soldiers (he only need Shang Tsung to acquire the souls, and with that now done, Shang Tsung is no longer needed). So if he can revive a dead soldier, how hard is it to revive a dead champion?
So with this, they bring back Liu Kang's body (wherever it went after he got killed), and bring it to "life". It won't be the 'true' Liu Kang, but they have the next best thing: a replica of the original - they have a zombie that cannot be killed (how can you kill something that is already dead?)! He was the chosen one, is the reigning Mortal Kombat champion, and is now at their disposal! What more do they need to take over earth?
Meanwhile, expecting that this would happen, the Elder Gods have prepared for it. They know that their only chance of beating this new threat is with the aid of 'the chosen one'. And from MK history, we know that the chosen one has been Liu Kang all along. They now need the help of the 'good' Liu Kang to assist them in this quest. They need the 'spirit' Liu Kang.
With that, that is why I think there are two Liu Kangs. The spirit (good) Liu Kang, and the evil (zombie) Liu Kang, who would be the new boss.
The 'deception' I would think would be that everyone perceived the Dragon King as the new evil power, when in fact the evil power is actually earthrealm's very own Mortal Kombat champion.
