Probably a rogue deck. Its happened several times before, and it is highly likely it will happen again.
A major drawback to playing archetype decks is that everyone knows what to expect. The element of surprise is little to none. Rogue decks, on the other hand, when designed and played well, can be quite unpredictable, and unaccounted for.
I am usually in favor of original decks. The ones that are successful generally demonstrate great understanding of how cards work together and their creators have spent a considerable amount of time and energy to make it into a force to be reckoned with.
This, of course, isn't to say that general archetypes are all bad- many of them have placed high at Worlds in prior years, while not completely reaching first place. Some archetype players require a lot of prior knowledge about game mechanics, as well as experience with their deck in order to fully understand how to play it well. I have a lot of envy for decks like DragTrode, BLS, and RAMBO (previous modified format) in this matter.
What I don't like is when a player copies a broken, easy-to-use, yet popular deck that took a long time to originally make, destroy everyone around them, and let their victories get to their head.
No matter which deck type makes it to first place (or even fourth) at Worlds, they definitely deserve recognition for their achievements.