Ngl it's hard to imagine even a third devil fruit putting him on the pedestal worthy of an endgame opponent. He needs genuine Haki feats which is severely lacking.
A lot depends on the abilities shown by Roger and Rocks during this event. Haki is a part of swordsmanship. I've always thought there could be more advanced techniques that could allow Shanks to still be stronger but that has yet to be proven.
It's said that all of the fiercest of the seas made it to God Valley. He's a year older than Garp and he was still Vice Admiral by the time Garp was having duels with Roger.
This flashback solidifies him as barely scraping Yonko level at his peak.
Saying this after the recent chapter doubling down on Ray and Gaban being the esteemed 2nd and 3rd respectively (or equal), how does Oden play a role in this hierarchy. I don’t recall if he’s considered a Roger member officially or honorary and whether he is being considered at all in the dialogue.
Is this just a coincidance? Not just the look but the color is the same in the manga. Dracula means son of the devil. Is Mihawk part of the Nerona family line?