With a combination of dictators-for-life in countries like China and Russia, and the collapse of the West because of populism, it is likely that a sea-change really is occurring and the outcomes will wreck the lives of hundreds of millions of people. So if we are approaching an age where large-scale alliances are a thing of the past (with the USA resuming its isolationist/protectionist stance that led to the Great Depression in the 20th century) and plenty of populist fear, hatred, and anger bubbling up everywhere, it seems likely we'll see a lot more violent conflict. This will be a return to normal, as the nearly-eight-decades-long peace in Europe since the end of WWII has been very atypical. Indeed, such a period of extended peace was last seen prior to the collapse of the Roman Empire.

So then the question turns to nuclear weapons. In a binary conflict, game theory and real life both show that an equilibrium can be reached where each side feels it has sufficient capability to deter the other side. But in a 3-way game this is impossible, for each player will want sufficient capability to contend with the other two players. We are therefore entering a wholly new phase when it comes to the business of nuclear weapons and this may very well be what ends up enabling us to exterminate ourselves. Which would be condign, given that we've wantonly exterminated so much life on this planet already...