It's not really a theory, but I see many people making threads asking or speculating on what the Legendary in 5.4 will be, admittedly, these people usually receive negative responses, which I'm expecting in the comments below from a few idiots, but, I've never seen anyone post this, I've seen one post saying they think it will be about the capes.
But I came across this, that Wrathion says when giving you the 600iLvl cloak;
"I can custom-tailor the cloak to your preferred abilities. Choose wisely!
The cloak contains only a fraction of its potential power. I'm already hatching a plan to augment it..."
Isn't it obvious? Was it overlooked?
inb4 "I already saw this", i'm expecting idiot comments like that, but with the amount of threads that have been made on it, there you go for the people that are rather confused.