Mihawk is only relevant for Zorofans, for those who aren't Zorofans Mihawk has zero relevance outside of being a oneshot motirial for Zoro–Mihawk doesn't play any role in the story whatsoever. But to be fair it might change in the future, Mihawk might gain some relevance after Wano, possibly due to Shanks, who knows!? But right know, to-date, Mihawk is completely irrelevant to the story, especially after the Shichibukai abolishment which gave him a place to be in the power balance; now, he's nothing.