Absolutely NO guarantee that Fury beats Usyk. Beating Captain Windmill while getting nailed several times by one of the most inaccurate champions in HW history does NOT mean he will defeat a significantly more skilled opponent in Usyk.
It is true that Usyk has never fought a giant like Fury but Fury has never come close to fighting an opponent with Usyk's skillset. I underestimated the Ukrainian once, I won't make that mistake again!
Hard to see how he wins an immediate rematch anyway. He'll have to come out all guns blazing to get the early KO leaving himself open to counters and gassing out.
As much as I and everybody rates Usyk, fighting Chisora, Joshua and Fury are 3 completely different things, Usyk has an elite, refined skillset, and elite footwork in combination with being southpaw which makes him a nightmare opponent for just about everyone.
Fury is one of the most versatile heavyweights in history, he can box and slug, he can fight on the back foot, he can fight on the front foot, he can box southpaw and he can fight orthadox, he also has elite level stamina to go 12 rounds, a high boxing IQ, and balls of steel when faced with adversity, Usyk is not facing a stiff, one trick pony body builder with stamina issues like Joshua.
The proof is in the pudding so hopefully we will see but I think Fury will do exactly what many were expecting Joshua to do to Usyk, and blitz Usyk with aggresssion and effective use of his weight at every opportunity, I don't think there is any chance Fury will be timid and gas like Joshua, and even if Usyk had success, Fury is a fighter with a plan B and Plan C unlike Chisora and Joshua. I'm not a big betting man and I do respect Usyk is a master craftsman but if this fight happens I will be putting a sizable bet on Fury to win.