We've lost, by my count, 1,394,100,000 jobs in the US in the last two hundred years. You may notice that is a larger number of jobs than people actually exist; this is because, if all those jobs actually existed, we'd still be farmers. (Value calculated by dividing current median income in the US by an estimation of sustenance income necessary to a lifestyle appropriate to, say, the 1700's. Not terribly accurate, as it doesn't account for the increased value of leisure time, or the automation of non-economic tasks; the actual figure in these terms may be as much as 30x rather than 9x the labor force. Additionally, I didn't include the massive reduction in work hours over the past two hundred years, which could as much as double that figure again)
The challenge isn't to figure out how many jobs automation will eliminate; it's already eliminated nine times more jobs than there are people doing jobs in this country. That's what permits our high standards of living; each person is enjoying the fruits of the labor of at least eight additional counterfactual people whose jobs are being performed by automation.
The challenge is to figure out to what extent this trend can continue; there's obvious room for improvement in that most of the world still has substantial improvements to be made to its standard of living. The challenge is to figure out whether or not the most fundamental tenet of economics - that demand is unlimited - holds true.
I always thought demand was limited by factors such as the size of one's stomach the speed at which clothes wear out or go out of fashion, and most importantly income among other things. I'm actually kind of surprised to hear that unlimited demand was a fundamental tenet of economics.
As Multiheaded added, "Personal is Political" stuff like gender relations, etc also may belong here.