Right before Miles is executed, he says:
You are fools! One day, the men of gold and red, bearers of the final metal, will come to you. And you will be ruled by them.
I've seen speculated on 17thshard that think the men of gold and red are people from the Southern pole of Scadriel. What evidence is there that points to this? Is there another possible explanation from elsewhere in the Cosmere? Given the connection to color in Warbreaker, could they come from there?
(And yes, I know Lightsong's colors are red and gold, but I know he isn't involved.)