Ace's death did not remove his presence from the story; instead, Oda used his absence to reintroduce the third sworn brother, Sabo. Thought to have died in childhood under Celestial Dragon cannon fire, Sabo had survived under the care of Monkey D. Dragon and rose to chief of staff in the Revolutionary Army.
During the Dressrosa Arc, Donquixote Doflamingo secured the reborn Mera Mera no Mi to lure Luffy into the Corrida Colosseum. Sabo secretly stepped into the arena, took Luffy's place in the tournament finals, destroyed the ring, and consumed the fruit. Inheriting the flame techniques was not a replacement of Ace, but a canonical continuation of his will. Sabo using the "Fire Fist" technique to incinerate Marine fleets echoed Ace's legacy directly into the final saga.
