I'll be surprised if Fujin or Bo Rai Cho don't make it as DLC sometime soon. They're literally important characters to the all-around story.
TBH, I'm actually kinda shocked at the number of returning characters to begin with, because when they were first promoting this game, it felt much darker than what the colorful array of characters we have now made it out to be. I mean, no offense to Cage family fans, but it would've been so much better had Johnny and Sonya died and Cassie was on this revenge seeking mission trying to stop Shinnok… and don't get me started on more than half of the ninjas making it…