I Thought Obito was at piece with his decision to entrust Kakashi and give him his sharingan. he said it was unfortunate that he couldn't have stayed longer with kakashi now that they had developed a friendship. He also said that he regretted not expressing how he felt about Rin. I always thought that Obito's sacrifice helped change Kakashi's ways, because of obito's sacrifice kakashi learned that teammates are more important than the mission. Just because Kakashi could not keep his promise seems like a pretty silly reason to want to cast the world under ultimate tyskyomi.