What happens if you defeat Khotun Khan at the beginning of the game - Ghost of Tsushima

I am really disappointed, I was really expecting something else, at least a cutscene or something. After around 12 hours of anger and despair, nothing happens :( . I feel like this is a missed opportunity from Sucker Punch, an alternative ending would have been awesome. I think they wanted to do something, but they gave up in the end because even if the boss is very very very difficult to beat, there is no indication that he is unbeatable, you can dodge and damage him, that’s enough for a gamer 😁 . Anyway,