At their best, I just can't see Golovkin beating Ward. Like, at all. Ward is bigger, and he survived Kovalev, so Golovkin's power wouldn't be a factor here. Ward is slick, a master technician, and can fight on the inside, so his style would be a nightmare for Golovkin. It would be a 12 round sweep. Ward by schooling. And GGG is my favorite active boxer atm.
You should watch Pirog's video when he speaks about GGG after Alvarez. He stresses that GGG has a large arsenal and that he is extremely skilled, but he is a hostage of his style. In fight with Ward I think GGG won't be a hostage of that style and he will show his skills in full and I actually think that only Ward will push GGG to show his best. At 168 I would think GGG will win SD or KO. At 175 Ward has much better chances getting SD or UD. That fight unfortunately didn't happen and would have been wonderful present to boxing fans.
Funny enough Macklin said that he low blowed Golovkin in an attempt to get him rattled. Golovkin didn't deviate from his plan a bit and kept ploughing forward.