Jevons paradox doesn't always apply (it depends on the shape of supply-demand curves) and it is entirely possible for technology to eliminate careers. For example, a professional translator can work far faster now than twenty years ago, but the result is that positions for professional translators are rapidly disappearing rather than growing. There's a finite demand for paid translation work and it's fairly saturated. There are also far fewer personal secretaries now than there were in the '70s. That used to be a very common and reasonably well-paying career. It may happen that increasing the efficiency of software development results in even more and even-better-paid software developers, but this isn't a guaranteed outcome.