The Archdruid was talking about making predictions that were based on historical data, rather than thought experiments.
A not very bold prediction:
Since the 18th Century there has been at least one major world war in each century. The big ones include French Indian/7 Years War, Napoleonic, WW1 and WW2.
Only in World War 2 was any restraint shown in weapon types used - the Germans did not use nerve gas, but both nuclear and biological weapons were used.
Except for WW2, which is often argued to be WW1 part 2, the initiation of conflict came from a very unexpected direction, to the extent that the start of the "big one" is highly unpredictable.
So my prediction is that there is a high possibility (to the point of a probability, but not a certainty) that we will face a global conflict where nuclear weapons are put into play sometime in this century.
What I find interesting is that the post apocalyptic fiction that seems the most dated are the nuclear war scenarios.
And just in time for a counterpoint, an article comes out that says that it is unlikely that the United States and China will go to war: Why the U.S. and China (Probably) Won't Go to War. It's argument, not a bad one, is that the U.S. and China are unlikely to intentionally blow up the entire world. My counter argument is that in 3 of the 4 world wars noted, there was not an intention of fighting out a long dragged out, empire destroying war.