How Did Macbeth Not Kill Duncan

Have you ever wondered what would have happen if certain characters didn't do or say certain things? Like what would've have happen if Macbeth didn't kill Duncan? I believe that Macbeth would have been a great leader. He wouldn't have any guilts, so he would actually lead the country in a good direction. Duncan would've probably sponsored Macbeth, therefore people would actually like him when he came to the throne. Banqou would still be alive, and with time he would've probably had more kids. Since the witches told him he wouldn't be king, but his children would be. The biggest thing I believe would have been in his favor is Divine Right. With that the universe would've not fallen out of balance, so he there would be peace. When he's time came