Zoro will surpass Oden and Ryuma by making Enma a "White" Blade, to purify it of its... uh... anger.
I wanted Momo to get Enma back, but now I think Zoro will end up with 4 Swords: 2 in each hand, 2 in the mouth (Sanji's CoCking can help widen Zoro's mouth, just need to make food the size of those jumbo ring pops that one guy on Tik Tok eats)
Wado/Nidai in the mouth, Shusui/Enma in the hands.
IMO Wado Ichimonji will balance both the "Dark" in the One Piece "Shadows", the aspect of Soul Moria used to make his Zombies, and the White "Power of Love" Sanji uses to make his flames.
Wado Ichimonji = Straight Line through the Path of Harmony/Harmony Path Beeline
Wado will be a Gold Blade, Black/White mixing together to form a "Sun"/the "Dawn"; a Black/White Blade in Harmony.
By killing Kaido with Enma, Zoro will eat Kaido's Fruit, turning Enma into a Zoan Weapon like Funkfreed and Cerberus.
By killing Kaido with Enma, Enma will become a "White Blade", allowing Zoro to finally surpass Oden as the strongest Samurai in modern Wano history.