Glenn (Instapundit) Reynolds links to a pessimistic treatment of economic growth by Michael Rogers.

In my little part of the world that sample has included advertising agency people, a television executive, two doctors, a lawyer, a retail stockbroker, a building contractor and several business and editorial folks in magazine publishing.

None of them was predicting doom, but they all saw tougher times ahead in their respective fields…

If he really wanted a pessimistic outlook, he could have interviewed horse-and-buggy makers.
My point is that progress always leads to displacement. The fields of advertising, medicine, law, finance, construction, and magazine publishing all are in the process of being re-shaped by technological change. People who do not adapt their skills to these changes will indeed find that their value has depreciated. However, people who do adapt, along with new entrants, will find opportunity.

In fact, I think that it is possible to be optimistic about overall economic growth and yet pessimistic about almost every existing industry! Over the next thirty years, many of the jobs created are likely to be for positions that do not exist today (just as “web designer” did not exist ten years ago) in industries that have not yet been born.