I'd like to see Kano. He was a ton of fun in 11 but it's looking like he may only be a kameo. I've also wanted Havik to return for a while. He was a fun character.
If he is in as a playable character I hope they give him a more rugged look. His Kameo outfit is a remake of his MK1 look, but I think they forget that Kano was not clean shaven in MK1; he had stubble and greasy looking slicked back, receding hair. It was his MK3 look that had him clean shaven.
I think a greasy unkempt look does well to show off his sleazy backstabbing criminal ways. Some of my favorite designs of his were MKX and MK11's. Hid Deadly Alliance alternative outfit was a really good remake of his MK1 look.
I also like the clean shaven look, to show his military prowess. In MK3, he was a specialist for Shao Kahn's side due to understanding Earthrealm's tech and weaponry, and he even ended up becoming a general for Shao Kahn. For the clean shaven look I prefer it accompanied by more dark colored tactical looking attire. The sleazy greased up look can go with pretty much anything though.
I think it would be a little sad to see Sonya and Jax miss out, bit that's looking likely. Jax, it appears will be DLC at least.
The character that I'm looking forward to the most is Ashrah. I always thought her design was pretty cool with the elegant white robes and hat, and the kriss blade. And her lore, being a reformed demon who now hunts down demons trying to purify her soul, it has some good potential. The Armageddon bios hinted at a rivalry between her and Nitara, and it would be interesting to actually see something come from that one day.
MK Deception had a mixed bag as far as newcomers go, and I think Ashrah was one of tnem that was underrated.