Vernor Vinge has a great article up titled "What If the Singularity Does NOT Happen?" Vinge originated the concept of the technological singularity, the theory that in the near future the rate of technological growth will approach infinity and result in the creation of entities far superior to humans in intelligence. While Vinge still regards the "singularity as the most likely non-catastrophic outcome for our near future," he is still willing to explore other alternatives in this essay.
I personally don't believe the singularity will happen in our lifetimes, if ever. Part of my belief results from observing all the failed science fiction predictions of the last 100 years. For example, where are those Pan-Am space shuttles and moon bases from 2001: A Space Odyssey? Or the inevitable nuclear war that was supposed to set humanity back to the stone age?
In addition, people who promote the looming singularity tend to focus exclusively on the technology aspects of human civilization and culture. However, technology is only one aspect--albeit a highly visible aspect--of human existence. Our civilization and culture also encompasses a large set of customs, habits, beliefs, values, and genetic and psychological programming, all of which are there to ensure the continuation of the human species. Of all the writers dealing with the singularity, David Marusek comes the closest to understanding how humanity might respond to the so-called event in his award-winning story "The Wedding Album," where he posits humans destroying every aspect of computer technology rather than allowing the singularity to happen.
So will the singularity come to pass? Maybe. But it's equally likely that computer technology will stall out (as hinted at in a recent AP article about the limits of ever smaller silicon computer chips, with Intel predicting that a number of "highly speculative" alternative technologies, such as quantum computing, optical switches and other methods, will be needed to continue Moore's Law beyond 2020). More likely, we will see a mix of these two extremes. But the looming singularity that results in the end of human history as we know it? I'm not holding my breath.