I haven't bought Mellisandre's stuff about Stannis being the chosen leader of the Lord of Light. It all was very contrived, her having him pull the sword out of the flames to meet the prophecy/gospel/whatever. Stannis even just sort of gave up the sword to a servant then like it was nothing he cared about. I took that to be foreshadowing from the director that it wasn't the real event.
Looked up the quotes from the show:
Quote
According to prophecy, the Prince That Was Promised would be reborn "amidst salt and smoke"
[3] and pull a flaming sword from the flames,
Lightbringer, to combat the coming darkness.
[4]
I think that event still is to come. With the "salt' part, wouldn't it be a trip if it was Theon?
Though my guess would still be it's Jon Snow, and we'll find out his mother Wylla gave birth to him on a boat or island or something.