Some say the world will end in fire, some say ice; others say it will end in the steely grip of self-improving superintelligence born of human hubris. Po-tay-to, po-tah-to.
On one hand, it's hard to imagine we'd be so foolish as to create a Frankenstein's monster without a fail-safe. But do you know what's not hard to imagine? That some garage hackers or industrialists, driven by rivalry, revenue or (Asimov help us) fetish, will sit nose-to-breadboard until they've created artificial intelligence or some weird imitation of it.
However it happens, the doom that follows need not come from so literal a source as a robot hand around our throats. A society unprepared for massive labor shifts and joblessness could face financial and social turmoil. Should society survive, millions of people will face existential crisis, whether in the form of a sense of futility or a headlong descent into decadence and dissolution.
Optimists insist that matters will self-correct, and economists argue that tech will create more jobs than it destroys. But even ignoring the risk that superintelligent machines will rise, self-improve and decide a femtosecond later to eliminate humans, we'll still face one of the most transformative moments in social and psychological history. Because however it shakes out, it'll be something we're not prepared for, and that alone will make it a disaster.