I agree, he won't LOOK like them.You guys keep forgetting that Nomura said that we will be surprised when we discover Vanitas's identity. Usually one of my first thoughts is this 'I bet it will be either Sora or Riku". So, with that piece of information in my head, I turn down that possibility. I'm not saying that you guys are wrong, I'm just saying my opinion.
He'll be connected to them though, that's my theory.