I do believe that another nuclear bomb will be dropped some day, but not in the way that you think. While this question may have had you think of countries attacking each other, it is actually something different. You see, countries test nuclear weapons a decent amount, and a large amount during the Cold War era. So, technically, countries have dropped nuclear bombs after Hiroshima and Nagasaki, but not in acts of aggression.
If I couldn't use that as an example, I still do believe that some day in the future, there will be another nuclear attack on a country. I do not know when it will happen, nor do I want it to happen (I don't think anyone would want that), but we have come close to nuclear war before. Humans are human, and mistakes can happen, let me tell you a story.
During the Cuban Missile Crisis in the 1960s, the U.S. and the Soviet Union came within a hair of nuclear war. During this time of crisis, U.S. and Soviet nuclear submarines patrolled the oceans, and during this conflict, one Soviet submarine prepared to fire a nuclear missile. According to Soviet military policy, three officers manning a sub must approve a strike before it can commence. Two officers in the sub approved a strike on the U.S. during the crisis, as they believed war had already begun (it was hard to communicate in subs during this time), but one officer denied the other two. Vasili Arkhipov, regarded as "The Man Who Saved the World" was the only thing preventing mass nuclear conflict. Had Arkhipov approved the strike, we wouldn't be around today.
These human errors that people make convince me that it is extremely probable that another could occur, and this could lead to another nuclear conflict.
