Kitana
Sonya
Jax
Johnny Cage
Kung Lao
Quan Chi
...not that I want all of these characters in, but I think they're the most likely canidates.
If I had my pick, I'd choose Kitana, Shao Kahn, Kung Lao, Khameleon, Fujin, and Kintaro. But I doubt that will happen.

you lucky gamecubers you...lol
if I had a gamecube I would love to have sektor, rain, fujin, kung lao and kitana

Shao Kahn
Kintaro
Rain
Reptile (MKII)
Ka-Tra

Sonya
Shao Kahn
Kitana
Frost
Nitara
Sheeva
Fujin
Kai
Shinnok

Shokan
Shao Khan
Shang Tsung
Frost
Kung Lao
Cyrax
Nitara

Sheeva
Rain
Kai
Fujin
Rain
Kia
Jataaka
Sareena
Shinnok
Sektor

Shao Kahn
Nitara
Sonya
Kung Lao
Kitana
Sektor
Sareena
SHEEVA!
Rain
Quan Chi
I would love these to be in the GC version, I would buy MKD on the Gamecube for those.

Aswell as Kahn, I would like to see:
Sektor
Mavado
Rain
and Kitana.

kahn
mavado
kitana
kung lao
sareena
sektor
im also expecting
cyrax
sonya
jax
johnny cage
nitara

Kung Lao
Sektor
Sonya
Kung Lao
Khan
Stryker
Kitana

Rain, Sektor
...cant believe I just freakin sold my gamecube aswell *ARGH*

I sold my cube recently too...useless thing.
But I think the following will be possible candidates for the GC version:
Rain
Sektor
Quan Chi
Shang Tsung
Kitana
Ninja Reptile
Reiko
I didn't mention Kahn since he's already confirmed.
I'm thinking that ninja Reptile and Rain will be pallete swaps of one another.

Sektor
Kung Lao
Kitana
Cyrax
I'm hoping some DA characters are in it. Plus they had a render for Sektor in the krypt.

I'm hopein for Goro and a ninja version of reptile, but I sold my gamecube to so I guess it doesn't matter.

My picks are: they are already in the game, all they have to do is bring then up to code.
Sonya
Kitana
Jax(Don't ask why)
Johnny Cage
Nitara
Quan Chi
Shang Tsung(think about it, if Shang Tsung died and freed Liu's soul, then he would be sent to the Netherrealm, but being he is a free roaming sorcerer like Quan Chi, it would be very easy for him to leave)
Frost
Reptile(DA & MK2 Ninja costume)
Cyrax
Kung Lao
A way to seperate Noob Saibot & Smoke with both of then getting another fighting style, weapon, and fatality.
Now the reason I choose so many characters is because it got me thing about MK Trilogy for PS1 & Sega Saturn, they in all had 37 characters in all in the game(maybe because they had alot of memory), so I think the Gamecube verson of MKD could put in more than just 1 or 2 extra characters for the lack of online play.

sektor will be in for sure, frost too, i just dont know how theyre gonna make up the styles for certain characters they gave their original styles too, i really feel its gonna be characters we havent seen before in the last 2 games

I reckon they will get 6.
Shao kahn
Goro
Kitana...pallete swap og Mileen plus DA primary as her alternate.
Sareena
Sektor
Kung Lao

here are mine
1.Shao Kahn
2.Kung Lao
3.Sektor
4.Goro
5.Fujin
6.Stryker
7.Kitana
8.Jax

Shao Kahn, Rain, Sektor, Ninja Reptile, Kung Lao, and Kitana (6 to make it an even 30).

Nitara
Frost
Sheeva
Sektor
Mavado

Kung Lao
Kitana
Rain
Sektor
Reptile (ninja)
Mavado
Shang Tsung
Quan Chi

My Picks for the GameCube include:
Shao Kahn(confirmed)
Stryker
Sektor
Rain
Plus more alternates for current fighters. I would love to see a Humanistic looking Smoke Alternate similar to that of UMK3. IMO Human Smoke in MK D is ugly.
The reason why I leave a lot of characters off the list, like Reptile, Kitana, Jax etc is because it would complicate the story more if those were in.
Now if Jax for example, came back possessed then that would be cool.

I'd love to play the Gamecube MKD just for Kahn. But Kitana and Sonya should return too.

Amen to that