I think that Zoro will eventually give Enma back to Hiyori and Tenguyama will in exchange offer Nidai as a WORTHY Enma replacement. Now, why would Zoro give Enma back after what he has been through with it? Well, mainly for two reasons: 1. Enma can't accept Zoro as his master–for whatever reason–and his "will" is unfitting with Zoro's. 2. Enma will always be something with Oden's spirit (whatever that means).
Just like with Sanj's raid suit, Zoro's Enma undermines Zoro's character and takes away from his achievements. Until this day we are not sure whether Zoro would be able to cut Kaido without Enma or not, and the entire Rooftop fight it was Enma that was getting all the attention from Meme and Kaido, not Zoro. And just like Sanji's raid suit was destroyed after he got his power up, I can see Zoro giving Enma back after he got his power up as well. I think that turn of events would be the best for Zoro's character.
Ur 2 reasons make no sense since :
1- If enma doesn't accept Zoro as its master, it just means that Zoro couldn't tame it and he wasn't measuring up to its standards which only belittle zoro's dream
2-Enma was never something with Oden's spirit (reread ch 1033)
Sanji's RS he received from his abusive family that caused him PTSD just from hearing their name is a completly different story from Zoro's sword that literally doesn't undermines or takes away from zoro's character or achievements in any sense .True enma was indeed getting all the attention from kaido and that's one of the reasons why zoro is going to the roof again,as for the desperate memes from sanjitards , no one gives a f about em since they will always find a way to downplay zoro whether he used enma or not lol. Also, didn't we literally know that zoro was holding back the whole time before he fought king? So by questioning whether Zoro is able to harm Kaido without enma or not, it only means that you are lacking comprehension skills.
Sanji is still dealing with his new germa powerups, so I don't really think destroying the rs was of any importance to Sanji's character.
In the end, I don't see how him returning one of the 2 the swords representing his Shimotsuki clan would be the best for his character ,not to mention there's no f way that would happen if he forged enma into a black blade lol