Let's assume for the sake of argument that new automation becomes cheaper and more effective than 70% of the human workforce.
They can't work, but they can still vote.
What kind of government are they going to elect?
a. One that lets the free market (now featuring very low demand for human labor) deprive them of any way of obtaining the necessities of life?
b. a government that forces re-distribution of a good chunk of the financial proceeds of the automated economy?
And if you try to disempower democratic government before this can happen...
Do we get a small cadre of libertarians, with their automation-fed bank/bitcoin accounts, protected by a robot army, surrounded by a horde of the zombie unemployed?
Sounds like a good video game actually.