The final scene shows Winston and the Bowery King (Laurence Fishburne) back in New York visiting Wick's grave with his pit bull: John is buried by his wife Helen, with a headstone that reads
Wick has been healed from gunshots before, as the New York doctor helped John at the beginning of John Wick: Chapter 3, and John could have been sent to the doctor following the duel. Nevertheless, Winston and John were in France, and there was no way John could have survived long enough to be transported back home to the doctor.
In the John Wick films, Charon's allegiance has lied with both Winston and Wick, but it's really his boss whom Charon owes most of his loyalty. Thus, given his servitude for Winston, and the way John Wick: Chapter 3 - Parabellum ended things, it would be illogical for Charon to return without his employer also coming back.