On Dr. Strange's choice and the paradox at the end of the Avengers: Infinity War

Warning: spoilery AF. I was annoyed with two things at the end of Infinity War, but I now think the Russo Brothers played fair, though they may have created a paradox they did not see. 1. Dr. Strange choosing to surrender his stone looks like he's choosing to surrender. 2. Killing off franchise characters who we know will return suggests the next movie will undo everything in this one, which