If John were the narrator in "The Yellow Wallpaper," the narrative perspective would likely shift to provide insights into his perceptions, thoughts, and interactions with his wife during their summer stay in the old house. As the primary narrator, John might offer a different perspective on the deteriorating mental state of his wife, potentially portraying her descent into madness from his point of view. This change in narration could influence the reader's understanding of the dynamics between the characters, shedding light on John's actions and decisions, and possibly exploring the impact of societal expectations on both characters. The story's tone and themes might be altered, emphasizing the complexities of the relationship and the consequences of the prevailing attitudes towards women's mental health during that era.
Hope this helps in the story, or the story you’re referring to!