Hi. I believe Mihawk will eventually be defeated by Zoro by the same finisher he tried in their first fight: Sanzen Sekai. Of course, this will be far upgraded with the power-ups Zoro has accumulated throughout his journey. It would be a great callback to show how far he has come, and if his swords are forged black, they won't break like last time, and Mihawk is surpassed in more ways than one. A full circle of Zoro's previous defeat and what Mihawk has taught him and his growth since.
So, the hypothetical upgraded attack would be composed of the following: En-ล Santลryลซ (King of Hell), Ichidai Sanzen Daisen Sekai (the bigger post-timeskip version used against Golem Pica), and even potentially Kokuto (Black Blade).
En-ล Santลryลซ Kokuto Ogi: Ichidai Sanzen Daisen Sekai
้ป็ไธๅ้พ้ปๅๅฅฅ็พฉไธๅคงใปไธๅใปๅคงๅใปไธ็
I know a mouthful. Anyway, what I wanted to mainly say is a crazy, out-there thought popped into my head. Mihawk's original epithet was supposed to be "clairvoyant," and all these theories exist of his special eyes and possible Nerona bloodline.
So what if Mihawk was able to see far into the future during the end of his first duel with Zoro? Maybe he saw his future loss by the same move and the same man. Hence why he strangely sweated during the final exchange despite being overwhelmingly stronger.