I don't think Tim Duncan would ever become a head coach in the league. He's way too mild mannered/soft spoken. I could see him as an assistant I guess, or in the front office.
I agree that KG might be clash too much with players to be a successful head coach. Same goes for Kobe.
Chris Paul I think would definitely have success as a head coach. Other than that I'm not sure I see anyone to be honest, at least as a head coach. Maybe JJ Redick? I know he's a pretty smart and well spoken,