The sorting hat just went "Uh haha not Slytherin? I don't care" and put him there. How would the story be different, and what would you have liked to see?
In the end, he still defeats Voldemort. But are his friends different? Would he deny his belonging in the House until the end? Would his importance and victory change people's views on the House?
And if not Slytherin, how would the story change if he was put in Hufflepuff or Ravenclaw?
He 100% would not be friends with Draco.
He already disliked Draco for his prejudiced views since their first meeting in Diagon Alley, before Draco even knew who he was. And even before he was sorted, on the train itself, he rejected Draco's offer of friendship and chose Ron, whom Draco was bullying and looking down upon.
There's no way he would befriend that bully
There's two types of people.
Ones who go through mistreatment, prejudice, etc. and it makes them bitter and treat others the same way, belittle them, so they feel in control and powerful, and so others feel what they feel. Why suffer alone?
And ones who know what suffering is like so they stand up for others so that no one has to go through that on their watch, making their conviction only stronger, rather than bitterness.
Harry is the latter. And that's also why he was put in Gryffindor despite having some "Slytherin traits" or whatever
But if he was put into Slytherin, I don't know if he'd befriend Hermionie, because they became friends later, but he already befriended Ron on the train, and rejected Draco all before being sorted. And he has friends in other houses as well already. Most of his friends would be outside of Slytherin and he would try to change prejudices he encounters and have good relationships with (the majority) of his teachers imo
Snape would still treat him the same despite him being in Slytherin because it doesn't change his father