The crazy thing is, if Luffy doesn't fall down and lose steam, I think there's a decent chance Ace lives--presuming of course he stops fighting Akainu like a fool, which I’ll admit isn’t guaranteed.
It was his gratitude to Whitebeard that slowed him down and his pride in his chosen father that led him to go against Akainu, but in the end Ace gives it all up to save Luffy. I've tried to point out all the times this arc where the focus has been on Ace's tattoo as well as the reiterated theme of wounds on a warrior's back being their shame, because all of Ace's pride as a pirate and a Son of Whitebeard is obliterated in service of saving his brother. Just like how his biological father Roger would face impossible odds to save his friends, and how Luffy does the same for the Straw Hat Pirates.
One Piece is not a series big on redemption nor is Ace a character that needs redeemed, but I do think that there's something to be said about how immediately after Oda shows how Ace's greatest flaws get him into trouble he flips things on their head but letting him die in an act of sacrificial love. Sacrifice without purpose is never portrayed positively within the series, but giving up your life to save the people you love is. Ace doesn't die as a dweeb getting rage-baited by Akainu, but as Luffy's big brother protecting him one last time.















