This is gonna be a hard one. The mathematics behind it are pretty beastly, but yes, there will be another war of the same proportion, one that would be a "world war" of its time. Well, there will be another war of this sort with 95% accuracy, anyway. It COULD never happen again, but that's unlikely, and existence doesn't like unlikely. Anyway, with 95% accuracy, the next war of World War proportions will happen between 1.55 and 2480 years from now.
Yes, yes, I made it math.
And those numbers, though fairly far apart, hold to 95% accuracy. Didn't see anyone else in here give a statement with 95% accuracy.
Oh, btw, there's good news:
With 95% accuracy, the human race will last at least around 5000 more years. So, we almost certainly survive the next World War. There's a small but finite chance that we don't, but once again, t's HIGHLY improbable.