Since Zoro has obtained Enma, something about it has bothered me, and I think I’m finally able to put it into words.
I believe that by the end of Wano, Zoro will give Enma to Momonosuke. You may be saying that this is contradictory to Hiyori’s actions, and you’d be right, however, the little insight we’ve gotten into Momonosuke and Zoro’s relationship this arc shows that Zoro has been teaching Momonosuke the sword, likely since the group left Zou.
This shows an understanding and a respect for Momonosuke’s declaration that he wants to grow stronger. Obviously not strong enough to beat Kaido now, but sowing the seeds for future development. After whatever usage he gets of the sword during Wano, I think Zoro will entrust it to Momonosuke knowing it’s relationship to Oden, and in order to allow Momonosuke to grow and inherit his father’s legacy, and as a sign of respect towards his student. Additionally, since Enma was given to Hiyori, it would reunite the two swords under a single user officially, and signal the path for Momonosuke to succeed his father.
Where would that leave Zoro in terms of swords? Well, there are other highly powerful blades currently in Wano, notably Nidai Kitetsu, Shusui, but I believe that Zoro will have a new meito grade sword forged for him by Hitetsu, the blacksmith who was Tama’s master.
This would give Zoro a sword of his own, and allow him to create a lasting legacy of his swordsmanship, much like how Shusui is a legacy of Ryuma, and Enma/Ame no Habakiri are legacies of Oden.
*Theory by NessTheGamer