OH i do have some ideas on mine but i wouldn't call them theories per se... i think yona is gonna take the crown (i like the idea too) because now more than ever, i'm sure she will want to work for Kohka and rebuild the capital. her journey has taught her a lot about her nation and its people. once su-won passes away, i'm confident she will serve well Kohka and make her best attempts to be friendly with neighboring nations like Xing. talking about su-won... one of the ideas i have for him is that i think kusanagi will let him die peacefully once everything is over, hak and yona being by his side. i don't see any miracles happening so... i think the curse will die with him (and mei-nyan). about the dragons, i think they will make it back, as humans. right now, Kohka retreated from battle so i don't think their powers will be needed anymore since yona's ruling era will be more about making peace than anything (surely, she will lead battles if needed). about hak and yona... i dont really see them getting married but they will surely still be dating, i believe kusanagi will leave that up to the readers.