TRMK got to interview Ed Boon, during the interview, Ed gave us some new details on MKX. One of the new details was about weather or not we will see a Mortal Kombat 4 character in Mortal Kombat X.
TRMK:
"Fans expect this game to follow the storyline of MK4 and beyond, but it looks like you are taking the story in another direction. Will fans see some familiar faces from the series they haven’t seen yet in MK9?"
Ed Boon:
"You will definitely see a Mortal Kombat 4 character, I believe that's the first time I've said that. You will also see some of the later game's fighters. You'll also see cameo's in the story mode. Some really fun ones."
So, basically, we WILL be getting at least one MK4 character, as well as some characters from the later games (which are Deadly Alliance, Deception and Armageddon). This isn't the only details we got though!
TRMK:
"Will you have to unlock Finishing Moves in a Krypt again like the last game? Like the Babalities for instance."
Ed Boon:
"Well the Fatalities won't. There will be a new "ality" that we can't talk about, but I'll tell you when we stop the recording, and there is a chance that those will require you to unlock them."
So yup! There will be a new "ality" introduced in MKX! Sadly, we don't know what it is, but at least we know that there will be a new "ality"! TRMK did say that "It's awesome I can't wait till it's revealed to everyone", but that's about it. If you want to read TRMK's full (3 page) interview, then check out the source below!
Source: "E3 2014 Interview: Mortal Kombat X with Ed Boon" - TRMK