Klitschko on points probably, but since Dubois can reach him, unlike most of Klitschko‘s opponents, it could be interesting if Klitschko got hit, Klitschko rarely got hit because he mastered the use of his physical advantages, physical advantages he wouldn’t have over Dubois, Klitschko rarely got hit due to his advantages, but when he did, he’d crumble and he wouldn’t have his usual advantages over Dubois, the only guy Klitschko really beat of his own dimensions was Jameel McCline, and Wach, the latter of whom didn’t use his advantages at all. Klitschko Wouldn’t be able to jab and grab, Dubois is strong and also couldn’t just slow down the pace, he’d have to find another strategy, maybe something similar to how he fought in the Pulev fight.
Klitschko would need his own personal ref that allows him hug grab and maul Doubis every 5 seconds. He would need to be allowed to lunge into Dubois with bear hugs like he did with Pulev. Otherwise DD gets through and works him over the way he did with Hrgovic
Klitschko wasn't much fun to watch but he became a clever fighter after his earlier losses. Chin was still an issue, but rarely lost his balance on attack, and had decent footwork, used his arms to block shots etc. He was also quite tactical and did different things against different opponents. We're still learning about Dubois. As things stand, I'd say Klitschko stoppage somewhere in the second half of the fight.
Wlad was a one trick pony , hit and hold was his only method of victory. If that didn't work he had no plan B , no adaptability. Refs who came down on him hard for illegal holding resulted in brutal losses - Brewster Life and death struggles -sam peter. Poor performances - Thompson , Jennings. And total dismantlement - Tyson Fury.
Klitschko is just too good a boxer for Dubois as he now is. I don't think Dubois can take Wlad's power and I don't think he has the footwork to close him off. Of course DD hits like a truck and a guy like him always has a chance but let's be honest, you'd have to favour Wlad.