Maybe. In my opinion I don’t think personalities are “states” people exist in, where those states can change and be reverted. Crow lives a different life than Uldren; as identities, they are two different people because they live different lives and made different life experiences. However technically speaking, Uldren and Crow are both the same people with the same brain. Personalities are largely formed through nature and nurture eg. Your physical brain structure and the way you’re raised/your influences. We can’t change his nature, but we can change his influences thus his personality. For this reason I don’t think “Uldren” is a static personality and I do not think he will make a full revert. What this means in terms of story. I can see Bungie taking Crow’s character down another dark arc, as with a lot of characters leading up to the witch queen. From a story writing perspective I don’t think it’s likely crow will ever fully revert back to uldren, but there is a lot of potential drama with his character waiting to happen. Bungies definitely gonna do something big with him.