If you are producing something at a price that your unemployed population can't afford, you will either stop producing it or utilise technology to make it cheaper.
If there is a demand, or indeed need, for what you produce then it will get produced one way or another. If there are people unemployed who could produce it, they will be employed to produce it. If robots can do it cheaper, then it will be done cheaper and people can go do other things.
Your great-great grandfather worked on a farm and spent his days ploughing behind two horses. Modern agricultural mass-production means you don't have to do that. Does that make you unemployed and the farmers no longer have anyone to sell their corn to? No, it means you work instead in a job in IT producing web-sites for companies selling fitbits that people buy to wear in their leisure time. An unimaginable way to earn a living to your great-great grandfather.
It it ridiculous to imagine that the changes brought on by automation and robots will be unique and something never seen before. Like previous automation, industrialisation and mass production, all that will happen is change. What was previously labour intensive to produce will become easy to produce. What was once exclusive and expensive will become common-place and cheap. Jobs that were previously impossible, impractical or uneconomical will become viable. Products for which there was once no demand, will come into demand. So people will go produce other things in other jobs that no-one ever imagined could be a job previously.