The problem with this is that Gandhi is Zoro's opponent:
- He wields a Supreme Grade sword
- All the other known wielders of Supreme Grade swords in the manga are at the very top of the World
- Gandhi has been shown polishing and cleaning his sword
- His sword is the Shodai Kitetsu:
- Zoro wields the Sandai kitetsu and indicated interest in the Nidai Kitetsu when he encountered it in Wano
- Even know, it's possible that he traded the Sandai Kitetsu off panel for the Nidai
Given the above two points, it's hard to imagine Gandhi fighting anyone
but Zoro.
Gandhi fighting Zoro heavily suggests the Gorosei are opponents for the Strawhats.
I can see that but my point is that Gandhi should not be above Mihawk at all (no matter what unless you have some massive temporary magical boost from an external source) and Mihawk should be Zoro's final fight (at least any sword/blade wielder). The other thing is that so far we have seen no difference between the Gorosei. They could be like Warlords with massive power difference between them or like Tobi Roppo with very little power difference among them. Considering their elite status and how they all seem equal we are talking about Admiral/Yonko or above level guys. Imagine 5 Shanks or Roger's, yes you can have maybe 2-3 fighters EOS with that much power on the heroes side but tell me do you seriously believe that anyone from the SHPs except Luffy and Zoro can fight anyone on Shanks and Roger's level 1v1 and beat them?
If the Gorosei fight the heroes and there is a significant power level difference then I can see Zoro fighting Gandhi. The only way this fight happens is either before Mihawk fight or after in which case the Gandhi guy gets some external power boost to be a stronger opponent than Mihawk. There is absolutely no damn way that a swordsman is stronger than Mihawk (he is the strongest in name and reality, there is no doubt about his title at all, it is the most confirmed and earned title of all World titles).
Not sure about the Kitetsu points cause Oda may just abandon that plot line like he did so many in Wano. Shodai Kitetsu wielder is so far only speculation. There is no need for sword drama for that fight. And if it is I think Sandai would actually mean a lot more than Nidai if we are going for that. Yeah we would all appreciate an upgraded sword, specially with Enma and cursed sword powers. But Sandai is actually the one true sword of Zoro in some way. Wado was not his, Yubashiri was gifted, Enma was given in exchange his but Sandai and Zoro chose each other.