We have moved from a world of ideological struggles in the 20th century to a world of geopolitical struggles in the 21st—or so goes the conventional wisdom. But technology is moving so fast that this world of geopolitical struggles will likely transform into another stage of conflict. Eurasia itself will become unhinged, as the destabilizing autocracies in Moscow and Beijing themselves become unstable.

In December 1997, I published a cover story in the Atlantic called “Was Democracy Just a Moment?” It was a time of unbridled...