Webdemon slayer's manga ending reveals the ultimate fates of tanjiro and nezuko, although some reading between the lines is necessary to get it all.
Webreduced role in the main plot:
Nezuko played a significant role in the beginning as tanjiro's primary motivation and source of strength.
However, as the story progressed,.
Webnezuko can control her demon instincts, giving her an advantage over other demons.
She has never consumed a human, defying her biological drive to do so.