More like how, not when.
How will they? Well, they need to make the wrong choice at an upcoming fork in the road. Automation will seize, over the next two centuries, 95-99% of all remaining jobs.
Even white collar jobs that traditionally require white collar intuition will be automated. Software is more and more capable of outdoing humans not just on a speed/accuracy front, but on an abstract, intuitive front as well. As we fill out photo captchas, we are training AI to recognize 3D physical entities in 2D formations of pixels. As we will out word captchas, we are digitizing books and archiving the human past.
ted.com/talks/luis_von_ahn_massive_scale_online_collaboration?language=en
Once this 95-99% automation happens, most of the human race will be unemployable, regardless of who their parents were, what kind of training they got, etc.
There will be some stalling of this process by giving people jobs that don't need to exist anymore as a purely symbolic gesture of good faith.
Then, there'll either be a luddite movement like never before... OR first world nations will all realize that unemployment no longer has to do with merit, and will allow the vast wealth created by automation to be redistributed to the common people so that they can stay economically mobile in a world where only the most innovative 1-5% people are even capable of getting a job.
If only one or a few nations do this, they'll suffer from immigration overload from the nations that don't, and collapse.
If no nations do this, governments will be rendered inefficient regulatory monsters, and Global Capitalists will sabotage remaining governments through lobbyism, taking over their functioning (as w/ USA right now).
We have two options, Cyber Socialism, or Coporate Feudalism. Global Capitalism will enable one or the other, out of pure necessity and the inevitability of the innovations it creates.
Mark my words. Save this post. Y'all can laugh when/if I'm wrong.