I think that if a person doesn't feel cynical then they're out of phase with the 20th century. Being cynical is the only way to deal with modern civilization - you can't just swallow it whole.
It isn't necessary to imagine the world ending in fire or ice. There are two other possibilities: one is paperwork, and the other is nostalgia. Eventually within the next quarter of a century, the nostalgia cycles will be so close together that people will not be able to take a step without being nostalgic for the one they just took. At that point, everything stops. Death by Nostalgia.