Though Dubois hit Usyk several times in the head, he did not hit him with ferocious shots therefore we do not know how Usyk would have reacted. On the contrary, a combination of Dubois not being anywhere near his best and Usyk not allowing Dubois to settle in to the fight led to Usyk winning. I was surprised at how Dubois boxed, it seems as though he entered the ring with the wrong mindset.
As for Usyk, congratulations are in order because at 38 year old he defeated a younger and very dangerous opponent to become undisputed heavyweight champion again. There is no reason Usyk and Dubois will fight again. Uayk will probably move on to fight Parker whereas Dubois (at 27 years old) has time on his side to recover and have a series of warm-up fights before trying for another title fight.