Aside from Mihawk himself, I am excited the most to see Shiryu's full display of power.
And judging by the pattern among Zoro's opponents, he cant possibly disappoint.
He was already a top tier swordsman in pre-TS, a man more dangerous than venom-man Magellan...
Then he obtained a very nice power for himself with the Suke no Mi that he surely will awaken into possible Nothingness that nobody known so far is able to cut.
There is also the possibility of Raiu having a nastier personality than Enma that forces his bloodlust and it can be a Supreme grade.
Then, on top of all that, the pattern with Luffy's opponents, he can obtain another DF, mythical Zoan and feed it to his sword.
It will most likely be Yamato no Orochi that Wano's Shogun didnt make much use of due to being a scrub.
If all those things happen...