Well I wouldn’t mind her reverting. After all, the feud between her and Dorothy is not over, and I don’t see any full redemption from her yet (maybe never). And to be honest, I prefer the villains as traditional bad guys, cause they are more thrilling that way.
For me, Zelena came too far last half season to have her revert back to her wicked ways. The whole arc, when you think about it, sort of was centered on her. I mean sure, the whole thing revolved around saving Hook, but the meat of the story was Zelena and Regina getting to say goodbye to Cora, her falling in love with Hades, her struggle with wanting to be good and wanting what’s best for her child, and then ultimately being the one who chose her sister over her love. And then she killed the villain of the arc. And then the moment the sisters shared after that moment was quite something and for her to revert back to her bad self, would just undo everything I never thought they could accomplish: redeeming Zelena. No, no, no please no. If anything, make it her split self. That would be fine because similarly with Regina, the writers can have their cake and eat it too.