News flash, Mihawk is so lacking in screentime because the nature of his character is to complement Zoro and act as his endgame.
In a one piece where Zoro don't exist, there's no reason to Oda be so vague with Mihawk.
There's no way for us to know how Oda would handle Zoro-less Mihawk in the story.
If we keep everything the same it is.
Mihawk without the Zoro loses all his best moments because he exist for those moments and would be a very strange character in a vacuum where we have no idea why he even exist.
Since he is handsome and cool that alone is enough for a small fandom, but he wouldn't be nearly as popular.
But you can be sure that at this stage of One piece, if Oda hadn't to keep him guarded from Zoro, we would already had development for Mihawk, and I am sure he would have other moment to replace his iconic ones.