We're about to round robin this business. This entire tale has been the bond between brother and sister, and while they have finally succeeded in returning Nezuko to human, as well as regaining her memories, Tanjirou now is the Demon... the situation has completely been reversed! It's Nezuko's turn to help her brother in his darkest times!
I'm wondering if the series will continue though. Will it end in another dozen chapters, with Nezuko dispelling the demonic anger, and thus fulfilling the circle (IE, Nezuko will travel with Tanjirou in hopes of regaining his humanity), or will Tanjirou escape, and become the next boss and an entire series of arcs will follow? I prefer the former. Heavily. Please leave Tanjirou alone... NONE of us want him to kill humans against his judgement. All of us want to see him go to heaven with his family. Don't let him burn away. Please...
On another note, Muzan's will to continue existing makes a load of sense. He finally concedes to the power of feelings, and their conveyance to each generation, admitting that it led to his death. As such, he decides to do it himself, and pass his feelings to the most vulnerable person. The guy who is literally dead and already has a bunch of demon blood in his system. I'm convincing myself this isn't BS basically.