Stryker, Cyrax, Smoke, Rain, & Kabal are all assists, so they're very unlikely. I know people are hopeful that this doesn't mean anything, but it clearly does as only unplayable characters are assists.
That leaves Noob, who hasn't made an appearance in any form in the game yet and with Sub-Zero confirmed to be Kuai Liang, he stands a decent chance, even with Johnny stealing his niche in his one variation. Sektor, who has yet to make an appearance in any form. With boon hinting that a cyborg makes an appearance, that cyborg could be Sektor. However, the supposed leak bios suggest he will not make it to MK X. Reiko, a popular character, thanks largely due to the comic. I have my doubts, simply because the comic needs a primary antagonist and that appears to be Reiko, who will likely die. Havik, appears to be pulling the strings in the comic and is a popular character, however, I can see them holding on to him until both the Orderrealm and Chaosrealm are properly introduced. Bo' Rai' Cho makes an appearance in the web series, will likely be mentioned in the story mode, and is a reasonably popular character and one of the few memorable characters from the 3d era. My bet is on him. Also, if there is a 2nd DLC pack, there is absolutely no way Fujin is not being included. He's not an assist, he's in the game as a NPC, with a re-design and he is possibly the most requested post MK 3 character. The final character, sadly for me, as I dislike this character, is Frost. There is a reason Frost survived the death match, only to be taken by the Special Forces. I know people dislike the idea of a Sub-Zero clone, but it's not hard to give her an original moveset/unique use of her powers with some imagination (Ice mirrors, snow diamonds, ice shuriken, ice walls, snow gliding, ice slides, etc.). Plus, the idea of a female Sub-Zero is a good sell for casual fans.
My guess:
DLC Pack #2:
Spawn
Fujin
Bo' Rai' Cho
Frost
