I think B-Hop would find a way to get the nod after having one of the toughest challenges of his reign.
I don't know who'd win but I know asking this question is putting GGG in an ATG status since you'd need to be an ATG to be considered a threat to BHOP in 2001 at 160.
And to note. I think GGG is a very good fighter. He is just nowhere near B-hop's level. Bhop is an ATG so that is no attack on GGG.
It's hard to even make a proper prediction in this one simply because GGG's biggest wins are Rubio and Murray.
That's actually one fight I give GGG a less than 50% chance in from modern middleweights. I need to see more, but I think Hops has a styles advantage over him as of now. No chance of a KO though.
Hopkins victories at middle do not stand out. GGG has too much activity, power and skills for a lower punch output Hopkins, who, by the way, was not a big puncher to win. Hopkins could not beat Taylor. Who was Hopkins best win at middle? Maybe Joppy. Please, De La Hoya was a blown up lower weight fighter and so was Tito. GGG wins here.