The good news about the Iranian nuclear situation is that it probably signals the end of traditional large-scale war, at least for countries with modern and near-modern economies. I say that because I predict economic sanctions will eventually work and Iran will allow inspections. When that happens, economic sanctions will become the go-to weapon of choice until someone invents an even nerdier way to wage war.
It helps that the countries with the biggest and baddest armies also have nukes and an incentive to keep the world order stable. And it helps that the Middle East will become less problematic as the world develops other sources of energy.
Meanwhile, the Internet will make it increasingly difficult for dictators to control information. And when dictators can't control information, they can't easily start unwinnable wars of aggression.
I think we'll see special ops attacks against terrorists for another hundred years or more. And obviously there will be regional skirmishes in parts of Africa and other sub-modern economies. But the days of big, traditional wars might be behind us. We've entered the age of Nerd Wars.
Nerd Wars involve cyber attacks, disinformation, economic sanctions, and other brain-over-brawn aggression. We'll see plenty of that for decades to come, if not centuries.
I can't rule out the possibility that North Korea or Pakistan will someday go extra crazy and launch nuclear weapons. But that sort of catastrophe will last less than a day or two in terms of the "fighting." I'm not sure that qualifies as a war. It's more in the unthinkable catastrophe category. And it would probably be caused by a technical error or other misunderstanding. It will look more like a tragic accident of epic proportions than a war.
I'll grant you that no one predicted Al Qaeda would attack New York City in 2001 and trigger wars in Afghanistan and Iraq. Wars come from unpredictable places. That makes me look a bit ridiculous to predict an end to them. But keep in mind that I'm not predicting an end to aggression in general. I'm only suggesting it will evolve from physical violence, which no longer works as well as it once did, to nerdier attacks involving information technology and economic sanctions.
Wars have always evolved from what works poorly (spears and rocks) to what works better (bombs and drones). At the moment, the weapons that work best are economic sanctions, disinformation, spying, and cyber attacks. Nations won't adopt those tactics because humans are becoming more enlightened or more peaceful; we will simply move to the tools that work most effectively, as we have always done.