The MKD story will be based on the Dragon King. It would be a complete waste to build up the story around him in MKDA and then just toss it aside in MKD. The Deception will be integrated into the story regardless of who the Deceiver is.

about the style thingys
it's probably like the Metal Gear Solid Trailers where they don't add all that stuff in
The dragon king will be in MK:De but we won't know for sure until it is released
It is true why the big build up if there is gonna be no DK

The Dragon King is almost certain to be in the game in one form or another. However, I don't think the build up to his big return is complete yet. I think he still hasn't reached his ultimate power, yet. I'd like to see Reptile contain the Dragon King's soul in his body, and Dragon King use him as a puppet to retrieve something that Dragon King says would restore THEIR power. When in fact it would exterminate Reptile's soul in the process.