Whitebeard's relevance ended in pre-TS.
He has only been a hype tool for either Kaido or Rocks in post-TS.
Mihawk's has ties and relevance with characters who arent Zoro.
Snitch, Buggy, Crocodile and maybe even Imu.
By keeping Mihawk only for the final saga which is the core of the story while everything else is like a filler to Oda.
Why is the most irrelevant guy saved up for final saga instead of other two who supposedly matter more?