In a future where
Humanity cracks the puzzle of cheap, non-polluting, abundant energy through cold fusion or efficient renewables.
Automation makes unskilled and semi-skilled labour obsolete.
The social disruption of un-employing every unskilled worker on the planet is completed via generational change, drastic social upheaval and maybe a crisis or two.
How does Capitalism and Representative Democracy adapt? Do they survive and if not what replaces them?
Representative democracy is leading to demagoguery and pandering to the masses. e.g. Heinlein suggested military service = citizenship = right to vote while Iain M. Banks' Culture has no laws or government.
I can't see Capitalism surviving without scarcity. So what comes with an age of abundance?
Similar Questions
What's the most likely "post democracy" form of political government? asks real-world next-step question without considering technology changes.
What would be the main societal changes if we invented a free and unlimited energy source tomorrow on earth? Closed as too broad. Hopefully my technology and focus on Capitalism and Democracy isn't too broad.
What would our planet look like with unlimited and cheap (i.e. almost free) energy? doesn't deal with societal organising systems.
Democracy
Democracy is the worst form of government except all the others that have been tried" - Winston Churchill
Thanks @Philipp for that quote. I don't think we'll revert to feudalism or monarchies. But Oligarchy is a threat plus I'm looking for something we haven't tried yet.
Those answers that believe Representative Democracy will not be affected by radical economic upheaval have not read their history.
Pre industrialisation only landowners could vote.
Women earned suffrage once they were an economic force.
The US War of Independence was fought against taxation without representation.
Change the organisation of the means of production and you will need a different system of government. It may remain a true representative democracy but current party politics and $20 million election war-chests means this isn't your fathers election anymore.
Edit
Not a duplicate of How would humans adapt if low-wage labor was done by robots? as I'm not asking how humans will adapt. Point 3 above says they've adapted. There are no longer unskilled jobs for unskilled people. Everyone who wants a job or vocation has one.
My question is specifically about organising the means of production which historically has been concerned the allocation of scarce resources in a post-scarcity world.
Secondly what impact does post-scarcity have on the most popular form of government on Earth (Representative Democracy).
Post-scarcity in this case is delivered by 1) Cheap abundant energy and 2) unskilled labor is done but automations. Yes other materials are still scarce, but those two get you 80% of the way to a radically changed basis of society.
Example answer
Here's an example answer: If control of the means of production remains with the elites (aka 1-percenters), and the majority of the population is economically unproductive and their inability to afford consumer goods wipes out discretionary spending. The entire economy shrinks because economic activity has decreased. In order to increase demand, consumer goods price deflation leads to a race to the bottom. Capitalism is in big trouble as the working and middle class is wiped out. Henry Ford sold cars because his workers could afford them. Oligarchs with deep and intricate ties to 1-percenters end up ruling for the benefit of the elites while couching the political rhetoric in populist and only superficially democratic terms.
However if education, arts, entertainment and leisure industries expand to fill the employment lost to automation, and wages and salaries are maintained, then the economy changes rather than shrinks and capitalism continues as usual. Buggy whips are replaced by automobiles. Representative Democracy continues to slowly evolve with media savvy candidates and representatives manipulating the news debate. It is possible that an Oligarchy posing as representative democracy overwhelms the democratic institutions over time.