They have said they might bring him back in a future DLC (hopefully not an Xbox exclusive *grumble grumble*) but if they don't, I won't be surprised if someone eventually mods him in. Someone has already recreated his clothing.
How can someone mod him in?
Chris said he was so important to the story that it was almost impossible to tear him out of it. (Not the exact words but something along this)
How can a modder know what kind of personality he has or what his goals are or hell even where to find him?