At the same, most of the reasoning about the future by even intelligent people still tends to involve linear extrapolation rather than exponential extrapolation - that's what makes sense to us. Thus it's more likely for a standard prediction is go wrong in the direction of the exponential trends continuing rather than in the direction of the trends stopping.
Moreover, one or another exponential trends might stop but the overall mine that Moore's Law comes out of, miniaturization, is not going to be exhausted at least until human construction reaches the nano scale.
Douglas Englebart had a pretty good approximation of what much of our information technology would be like today over 40 years ago.
http://sloan.stanford.edu/mousesite/1968Demo.html
Of course, this was because he put together all of the necessary underlying technology. I remember reading an interview with him in the 90s, asking him if he was surprised how fast technology was moving. He replied, no, he was shocked how long it took for the things he had working in the lab decades ago to reach the main stream.
That's the entire point of this (sub)thread. Making predictions of the next 40 years based on the last 40 is likely to lead you astray. A whole bunch of things are coming to a head. Coming revolutions in biotech alone are likely to seriously shake things up, IMO.
We consumers actually don't do that anymore: http://en.wikipedia.org/wiki/Concorde
40 years doesn't tell you much about the next 10.
Growth rates in recent times have depended largely on finite resources, many of which are now becoming scarce. It may be that we innovate around all of this, but it's far from certain.
Maybe we are really limited by available resources. We know for sure that we have limited supply of the solar energy. At the other hand, we are just using what is available on the surface of the Earth. Maybe we are going to figure out how to utilize more resources outside the surface of the Earth, or efficient way to use and recycle resources.
For many reasons I doubt that the last few hundred years are going to tell us much about the next hundred. So many critical trends are following exponential curves that can't continue on indefinitely.