According to Modesitt, it won’t happen because such visions are based on technology, not on humanity and they’re based on a western European/North American cultural chauvinism.
He goes on to explain:
One of the simplest rules involved in implementing technology is that the speed and breadth of such implementation is inversely proportional to the cost and capital required to implement that technology. That’s why we don’t have personal helicopters, technically feasible as they are. It’s also why, like it or not, there’s no supersonic aircraft follow-on to the Concorde. It’s also why iPods and cellphones are ubiquitous, as well as why there are many places in the third world where cellphones are usable, but where landlines are limited or non-existent.
All in all I think he makes a well-reasoned and cogent argument that completely misses the point. The point of the singularity is the premise, which I think is valid, that it is possible that a technology can arrive that completely overturns the basic assumptions we use to model the future. AI and nanotech are the oft-used sfnal examples, but history is already filled with basic advances that remapped the entire world to fit them: agriculture, sewage treatment, the printing press, anesthesia, automobiles, air-travel, television, the internet, cell phones.
But my main problem with Modesitt’s argument is that it is primarily an economic one, based on the assumption that the basic economic rules are somehow set in stone and aren’t manipulated by technological change. That’s only true if you’re very broad in defining your terms. A product’s value is less and less defined by the cost of the materials and labor required to build it, more and more the impetus to distribute technology is to get the end user to buy into an associated service (psst, wanna free cellphone, how’s about an inkjet printer, brand new DVR, just sign this contract) and as fabrication becomes more and more efficient, “things” become more like intellectual property where the cost has little to do with the physical object, counterfeits become ubiquitous, and theft starts meaning some basement entrepreneur is making something that looks too much like what you’re selling. The labor theory of value breaks down in a replicator economy. Even his points about energy becoming more expensive is one good fusion reactor away from being moot.
Like I said, IMO his argument is basically why the Singularity won’t happen. . . right now.