For this fight, both needs to be in 100%, mind games might also play in this one, Usyk is taking advantage of Fury's lackluster performance and for sure he will stick it out during their press conference. But for me, size does matter in this fight, so Fury despite his poor performance against Ngannou, will try to be better here and win thru judges card by unanimous decision.
I think we are in agreement with each other, for this fight Fury will try to be better than in his performance against Ngannou and to be clear, if he is as bad then he will probably be knocked out by Usyk. Having said that, I expect Fury will be back to his best and also think Usyk will be back to his best after his recent fights. The boxers will be looking forward as they try to make history.
I am almost 100% sure that we will never see such exotic fights. If Usik beats Fury, he will simply retire immediately and go undefeated. One of the big boxers (I don’t remember exactly who) recently expressed this idea and I completely agree with it. If Usik loses, then maybe we will see a Usyk-Wilder or Usyk-Zhilei fight and maybe a rematch against Fury, but then, regardless of the result, he will leave. He doesn't look like someone who would abuse his body even when his age does not allow him to maintain a decent shape.
Whatever happens in the ring, the outcome will have a sizeable impact across the boxing world. Will the winner of the fight even make one defence of their unified title? The chances are they will try to make at least one for the money but best really should know when to quit.