If Oda gives Muramasa to Zoro, that’s basically the end of the line for the character.
The very existence of that sword brings Zoro and Nasujuro to mind. They are the only two swordsmen with an Asian aesthetic confirmed for this final battle. At a stretch, you could argue that Shiryu might use it, he has a red Meito called Raiu that could be replaced or complemented by Muramasa, which would likely be red too.
It would be cooler if the Gorosei fought using a Nitoryu style with Shodai Kitetsu (owazamono) and Muramasa that would be badass. And Zoro would unlock the black blade grade during the fight by overcoming a buffed up Gorosei wielding a magic sword from the Void Century.