I was only looking at the past 40 years, much like the original poster. My edit clarifies this point.
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.