If they fight, one will lose his career forever. Well you can say - that is boxing, it is what it is - but ask youreself this who gains from them fighting, who can now in heavyweight division breathe little easier if one of them is not around anymore - everyone including the fans, especially Wilder, Fury, Ruiz and even if he has great chance, Joshua wants no piece of them. Look downwards, top contenders all call out Usyk, from Bakole to Makmudov to Anderson, Sanchez, Parker, they all wanted to be there, be the top dogs, now they cant, they have to pass through Hrgovic and Zhang and they wont because they cant. I dont see any of the contenders beat Zhang or Hrgovic, and now if they are both around, both attacking the titles or defending number 1 spots, there cant be any fake contenders (except Char). The era of fake boxing where a guy like Wilder can defend 10 times against people who are not contenders, AJ picking his opponents, Fury straight up refusing to unify, refuses to fight not only contenders, but boxers all thogheter, might be over.
You do realize they already fought and it didn't bring either down, they are both in the positions they are in. Why would a rematch?
Hrgovic is Usyk's IBF mandatory, Zhang is Usyk's WBO mandatory. Hrgovic should fight Usyk next. Zhang should stay busy with someone on the level of Dubois or Chisora, and then fight for the title next year. Fury will duck Zhang, Hrgovic and Usyk, and seek softer opposition.
Ideally Hrgovic will fight Usyk and Zhang will fight Fury, with the winners facing each other sometime in 2024. AJ and Wilder can fight in the meantime. A man can dream...