Fury proved himself clearly better than Wilder over their trilogy and no doubt Fury wins prime for prime. However, with how Fury has lived his life he is likely to deteriorate as a fighter much quicker than Wilder and arguably has already shown signs of this in his last two fights. The result of Fury Wilder 4 would not be a certainty and the later it happens the more it favours Wilder.
Wilder will deteriorate quicker. Older More injuries. Less skilled and fundamentals. Relies on physically. Wlad fell off hard at around 38. Wilder doesn't have his skills. It will be bad.