Everything else doesn't make sense at this point. Luffy is already reaching a level of being potentially the strongest. And Im seems to be the counterpart to Joyboy.
Headcanon.
Oda doesn't write his story to satisfy the powerscaling fantasies of his readers.
Fight happens because the plot want them to happen. And Luffy vs Akainu is one of the most built-up fights in the series.
Actually, 650 isn't that important. In fact, the first time Jinbe mentioned Akainu's and said he had a fight with Aokiji, Luffy wasn't triggered at all, rather curious:
650 literally is a chapter titled "Two changes you must know about" and that focuses on BOTH Blackbeard and Akainu
This is Oda setting them up as the two major obstacles for Luffy to overcome post timeskip. And this parallelism has been going since pre timeskip.
His scar only itched as he heard of Akainu emerging victorious. But scar-itching is a common theme; Kaido's scar itched when being reminded of the long dead Oden, Shanks' scar itched when he watched Blackbeard.
You're not making a very strong case for why Luffy vs Akainu won't happen here.
Mihawk scarred Zoro and they'll fight
BB scarred Shanks and they'll fight
Kaido and Oden are nemesis/arch rivals and fought
Luffy vs Akainu WILL happen
Also, what was the narrative during and post the war and post timeskip?
> Luffy overcoming his trauma, remembering his friends, wanting to become stronger
> Shanks saying to Luffy that it is ok to cry, but after that a man should move on
> Ace living and dying without regret, accepting his fate as a pirate
> Luffy relying on others, as "making those around him his allies" is his biggest strength
> Sabo inheriting both Ace' power and will, with people commenting on how similar Sabo and Ace are,
> With Sabo regretting he could not save Ace, and although forgiving himself, upon roasting Burgess, saying that it seems that Ace however still hold grudge.
I mean this is literally nonsense.
Luffy has moved forward, that doesn't mean he gives no shit about Ace's murderer, he refused to let anyone he doesn't know get their hands on Ace's fruit, told Blackbeard he would never let he of all people get Ace's DF and his reaction to Akainu being name dropped proves he has strong feelings of hatred for him.
Furthermore Luffy ALWAYS carries on grudges, he literally beats up villains for doing wrong things to his friends or people he just met. One Piece has ALWAYS been about revenge
Ace's grudge is against the BB pirates. You know the crew he was chasing around for killing Thatch.
And don't make me drop the panels where all of Luffy,Chinjao AND Oda state that beating the ADMIRALS is a requirement to surpass Roger
So I don't see how Luffy, who now became Joyboy, will beat Kaido and be basically lead the world against the WG, will be the one to face Akainu due to some past conflicts.
So in short you don't see how narrative build up and story relevance matters more than your headcanon powerscaling opinions which tells you Luffy fighting Akainu doesn't make sense?