The next war between nuclear states will probably go nuclear in the later stages as one side begins to lose. Then we might all just kiss our asses goodby - unless there is an intervention by ______.
Mixed nuts spillin' out all over the floor. Sheesh. Anyways, think of it like this: if it happens, you won't know about it anyway. Kinda like an Englishman during the V-2 thingie in WWII (the whole point of Gravity's Rainbow): if you were the one, you never knew it since those things were coming down faster than the speed of sound. So relax. Whether it happens or not will make no difference at all to you. When it starts it'll be over and you'll be - well, actually, you won't be.
I thought we would already have one a few years back. Maybe wait for the signs? Like a massive devaluation of a country's currency. Or some massive move in a currency that owns a particular country. Like Oil, gold, etc.... Or perhaps a major country attacking a very small country to tell others they are ready for war. Or wait for some sort of food shortage or lack of food stamps. Once you get hungry, you get mad.
The worldwide trend is toward less violence and more understanding, inter-dependency and communication. This makes large-scale war less likely. However, as the rising population starts to bump against the limits of the earth to sustain it, and as the climate changes and the seas rise and severe droughts become more common, wars between neighboring countries over land and water will also rise.