There is a great deal of interesting conversation around the topic of 'What if the Singularity Doesn't Happen?' Or what if it doesn't happen all at the same time. The latest issue of H+ magazine offers a glimpse into the idea that strong AI doesn't happen. What could still be built at a nanoscale without an AI doing the designing for us?
Neal Stephenson's The Diamond Age posits a future in which there have been few, if any, advances in AI from the current standpoint, yet nanotech is everywhere its visionaries hope it will be. Zeppelins composed of diamondoid spheres filled with vacuum float serenely over societies fractured by a complete disintegration of the geographically based Nation-State in favor of the 'Phyle' in an era when the size of your borders is the area you must defend from nanotech incursions.
But perhaps the most compelling single article on this topic comes from Vernor Vinge, who coined the term Singularity. He suggests three scenarios for if the Singularity doesn't happen.
The Return to MADness is the nuclear winter scenario. Pretty classic.
More interesting is the Golden Age, in which we decide to stop at some point. After a gentle recursion as populations balance, we enter a static state of blissful lack of progress.
The final scenario he thinks worth mentioning is the Wheel of Time. In this scenario, a mixture of the other two occur. Every time Humanity gets close to the Singularity, somebody pushes a big red button and blasts us back to the stone age, but not to extinction, starting the cycle over. In a sense, this scenario has our current state of being acting as a golden age, and getting much further than we are puts us over the edge.