is that when you're looking for precedent there are always those two little words: "it depends". You can't count on history to repeat itself.
I don't think there's a fundamental economic principle that says, "productivity increases actually increases employment." Yes, it *tends* to do so. If the next dollar of labor produces fifty cents of income, a firm won't lay out that next dollar; but if it produces *two* dollars of income it will.
However that scenario assumes that demand for the product is "elastic"; that if you drop the price a little you'll sell more, and make more profit. Suppose demand for a product is *inelastic*, that dropping the price won't get you much more in units sold. If the market won't buy more widgets at a lower price, then it makes sense for a firm to lay off workers as productivity goes up.
In the past the fear that greater productivity would result in job loss tended not to come true. At the outset of the industrial revolution nearly everybody would be considered materially poor by modern standards. Even in my granfather's generation it was common to by new clothing just once a year, and nearly everybody mended their own clothing. When computers were introduced to do things like payroll, yes the people who manually processed paychecks lost their jobs, but businesses responded by demanding far more complex and timely financial information products.
Now we live in a different world now. Almost nobody darns socks or turns collars; they throw worn or even stained garments away. Clothes shopping has become a pastime, not an annual ritual; many people shop every week. Financial products turn on split-millisecond timing, and are so complex you need an advanced degree in math to understand them. It makes me wonder whether we might be approaching a kind of productivity/demand singularity.
The biggest problem with predicting the future isn't *what*, it's *when*. People were attempting computer tablets decades before the iPad, but until the processor, battery, software and user interface technology were all available it was an exercise in futility. Much of Steve Jobs' genius was a matter of timing, of sensing when there was an opportunity to be created. I think there may be a productivity singularity in our future, a point where our established wisdom based on past experience fails. But I can't say when that will occur. I'm certain the market has surprises in store for us, but in the short term at least they'll probably tend to confirm established wisdom.
disclaimer: I am not an economist. But I *do* write science fiction.