If Usyk doesn't fight Fury again is there any other Heavyweight that could give Usyk problems ?

I think Zhang is too much of a plodder, Wilder is probably past it and too one dimensional and limited, Usyk's already beaten Joshua twice, Joyce is too slow and lumbering.

Realistically probably...

If Usyk doesn't fight Fury again is there any other Heavyweight that could give Usyk problems ?