I guess they do what humankind has always done, figure out a way to survive, aka career change :-)
A similar scenario is happening to most of the jobs that pay under $20/hour, right?
http://www.wired.com/brandlab/2015/04/rise-machines-future-lots-robots-jobs-humans/
Good news is that previously when people were given lots of leisure time, good things happened. First in the ancient Greece, all these philosophers started to pop up and think about things. Then, later on, Europe's aristocrats, bohemian's and scientists invested time and money in science, art, music, literature, etc. and that's why we have now knowledge of science, great symphonies, operas, classic books, paintings and stuff. So maybe jobless future takes the humankind to the next level in culture and science?