This is an interesting fight. I would be curious to see how Golovkin closes the gap because he hasn't fought anyone with Nunn's height and reach that I can think of. Nunn was a pretty big middleweight and I think could keep Golovkin off of him. Nunn UD but GGG has his moments.
I think that this fight is an outlier as he never showed such explosive fighter at world level outside of this one. He caught Kalambay with a beautiful shot but I doubt that if they fought another nine times whether he would be able to stop him.
I agree with this. Wouldn't be surprised if Golovkin gets to Nunn here and there and eventually stops him, but Nunn at his best presumably wins by decision.
What isn't speculation however is the rest of Nunn's career, both prior and post Kalambay. Nunn isn't much of a puncher. He's respectable when he plants his feet much the same as most any world class fighter. The Kalambay result was a once in a career thing for him.