This would be a 50/50 fight. If Kovalev comes 100% conditioned he may outpower Golovkin in a 10 round barn burner. Otherwise, Golovkin's relative lack of height would play to his advantage. Kovalev's body would be right in the Golovkin's power plane. Golovkin tires out Kovalev and takes him out to the body in the 9th. Boxing fan can dream...
Styles make fights, and this fight would be a boxing fan dream. Golovkin would have to go Tyson on Krusher, with bobbing and getting low while throwing those body shots. Could GGG take those head shots that Krusher WILL land????
He wouldn't be able to take them for long if flush, no one can (except maybe 175lbs version of Provodnikov). But Golovkin is very good at mitigating blows, his chin is always tucked or protected by a glove or shoulder.