According to Kojima, this character is not Colonel Campbell
One character that appeared in the new MGSV trailers has people debating: a man with sunglasses wearing a Diamond Dogs beret. Some argued this may be Colonel Campbell, but if we are to believe Kojima, it’s not him.
During an E3 interview a journalist of Game Informer asked Kojima about it, and he answered Colonel Campbell was not in the trailer. Let round two of the speculation begin!
Source: Game Informer

daaah….its Kaz Miller ffs….. no one noticed his right arm missing…..and if his shades didn’t gave him away i don’t know what will….
agreed. FFS is right. the guy is wearing aviators for goodness sake. and um yes his ARM is missing, hello?! debate closed… hahaha.
I can’t believe people didn’t notice the missing arm and the Diamond Dogs logo on his beret.
What people are debating this it’s obviously miller.
What? It doesn’t take a genius to realise the he is Kaz. Look closer detectives: Right arm missing, left leg seems clearly a prosthetic, and that face. Yeah, it’s Miller.
His face doesn’t look that much like Miller’s though. Maybe it’s just the shot.
Yeah, a friend of mine said the same thing about his face. He said that he gained a lot of weight! 😀 It’s just that we haven’t gotten used to his new clothes and berret. And the shot from the camera also.
ehh it’s Miller.
was hoping it was Gene to be honest.
i do wonder if Gene or Solidus will make an appearance here
it’s probably solidus cause he looks like snake