As I was doing this questline, I was listneing to the Silver Shroud radio station. The Shroud and his Accomplice (dont remember her name Mysterious Woman or something) were tracking down robots. Thats hint number one. To even solidify this statement, the Shroud goes on to say:
"No! It cannot be! Their leader is a robot! No, not a robot. A man in a robot suit!"
He even goes on to state that the man is "The Evil Mechanist."
Now I do not believe we will be meeting the "Mechanist" from Fallout 3 due to the fact that whoever lived was completely up to the Player. It is not completley ruled out though, and is still possible.
However, due to the fact that The Sole Survivor played as the Silver Shroud and attempted to stop evil doers, would in turn potentally spark a chain reaction for others to do the same, or opposite...
I believe we will be getting a companion or two with this DLC as we traverse the wasteland as the Silver Shroud seeking out the Evil Mechanist and put a stop to his evil shcemes. Honestly, this sounds absolutely amazing to me. I loved the questline and a branch off of it with an actual Villan?? Thats just amazing.
Keep in mind this is all a hypothesis and not supported by anything else but my own persom experiences and thoughts.