could the story of the novel exist without the class difference between amir and hassan?

One of the important layers to this story is the class distinction between Amir and Hassan. Amir is a higher call than Hassan. This limits their relationship to certain parameters. Amir controls the kite while Hassan is the runner. This casts a distinction in their relationship that permeates their relationship. When Hassan is raped by the village bully, Amir has not legal or culturally moral reason to intervene. He doesn't and the very human guilt haunts him. Amir's guilt even seems to transcend Hassan's humiliation. AS the story progresses, class distinctions become blurred. In the end Amir adopts Hassan's child and moves to the United States. This even further erodes the class distinction that limited their relationship at the beginning of the novel.

A little better version of the above:

One of the important layers to this story is the class distinction between Amir and Hassan. Amir is a higher class than Hassan. This limits their relationship to certain parameters. Amir controls the kite while Hassan is the runner. This is a symbolic distinction that permeates their relationship. When Hassan is raped by the village bully, Amir has not legal or culturally moral reason to intervene. He doesn't and the very human guilt haunts him. Amir's guilt even seems to transcend Hassan's humiliation. As the story progresses, class distinctions become blurred. In the end Amir adopts Hassan's child and moves to the United States. This even further erodes the class distinction that limited their relationship at the beginning of the novel.