You seem to be assuming that knowledge-based workers can deplete the corpus of knowledge work.
I don't think that's the case; once one program is written, another will be needed, once one drug is discovered, there will be still more diseases to cure and more side effects to eliminate.
I'd even go so far as to say that knowledge work is growing and will continue to grow - The more you know, the more you know you don't know, right? There wasn't a need for working on computers or airplanes as short as a century ago. Now how many people are employed in those fields?
My assumption is that growth in knowledge work is dependent on there being growth in disposable income for the population. In my scenario where a large portion of the population has no marketable skills and therefore can't find a job, this effectively puts a cap on the amount of knowledge work the economy can sustain. See my reply to stretchwithme for a further explanation of my thoughts on this scenario.
The growth in knowledge is dependent on how much brain power there is. Everything we do is subject to improvement by anyone that cares to analyze and innovate.
In the scenarios of those against technology 50 years ago, they also could not see how the economy would evolve or how people would adapt. But that lack of vision isn't proof that they were right.
I don't think that's the case; once one program is written, another will be needed, once one drug is discovered, there will be still more diseases to cure and more side effects to eliminate.
I'd even go so far as to say that knowledge work is growing and will continue to grow - The more you know, the more you know you don't know, right? There wasn't a need for working on computers or airplanes as short as a century ago. Now how many people are employed in those fields?