I don't dispute that nuclear weapons could come into play again in the future, just that a truly global thermonuclear war is much less likely now than in the past. Sure North Korea might try to launch a nuclear missile or two (coincidentally they just threatened to do so today) and get wiped out in the process, and yeah, some terrorists would probably love to detonate a suitcase nuke somewhere, but that's not the same thing as a truly global event that threatens all of humanity as we know it.
During the Cold War there was a really good chance of that happening, and there were several instances where equipment malfunctioned (and showed impending missile launches when where there was none) and the only thing that stopped it was the right general making a smart call that it wasn't real, or several other close calls, from global destruction.
North Korea isn't likely to bring that about. The Middle East isn't too likely to bring that about. India and Pakistan aren't going to bring that in either.
Russia is still capable to do that, but I think they're not too serious about their desire to actually go into war and are more taking advantage of NATO's unwillingness to go into war to make a few small land grabs (that was a little scary, though).
The tension and complex web of polar opposite alliances across the whole world just isn't there like it was in WWI, WWII, and Cold War days. It could still develop in the next decade or two, sure, but I really don't think we're there right now.
For all the ills that Capitalism might have, I do think it's helped tie all the countries that participate in it to each other's fates, to a certain extent, and they don't want to see the other countries fail (or attack them directly) since it will now affect their own economy, probably for the worst.
Trump is a wild card, but I think assuming he won the nomination he'll calm down his rhetoric, since he needs to in order to win the moderate vote anyway. If he actually made it into office, then that's admittedly a wild card. I'd like to think that he didn't actually believe that shit he said and will be more concerned with internal politics than foreign, and/or will head the advice of people who have been there a lot longer. Hopefully.