What happens to economics in a futuristic world?

[Associate Justice PiT]

All (or almost all) economic theory derives from the concept of scarcity.  If things can be made almost literally out of thin air or if energy becomes virtually free then that concept no longer applies and economic theory for the economy is no longer valid.

The economic theories that can be transferred to other things, such as daily life, would continue to apply as long as time is a scarce resource.

This.  I will say, certain jobs will basically always exist - inventors, software developers (or whatever is powering these machines in the future), and high-level management positions, not to mention plenty of academic disciplines based on research.  As long as there are products to develop, someone will have to formulate ideas about what they want and translate it into a product - certain aspects of this creativity process simply can never be automated, and people will have to decide how these firms go on.

I agree but for a slightly different reason.

Basically human wants are unlimited and resources are scarce. Resources will always, to some extent or another, be scarce in relation to human wants. It's possible that humans just become complacent and their wants decrease, but I doubt it. Plenty of people within this 7 billion and growing population will just want even more things that go beyond whatever earth and nearby asteroids can provide us.

Needless to say I don't envision a post scarcity society within my lifetime.

It may be a while for people who want to create and own their own solar systems as private property... but really, just about everything we can want or need can be made from matter within our solar system. Even if the population becomes steady at 20 billion people or something at some point. The Sun itself contains a lot of mass, siphoning off .00000001% of it each day and also using some of its energy to transform that matter into whatever we want would be more than enough to satisfy almost all material wants. (Think the Star Forge, used for peaceful and positive production.) Combine that with extreme recycling, advanced machine networks, nanotechnology, asteroid mining, etc. The only real concern will be real estate... but once we reach a steady population, even that can be managed with ocean cities/homes, underwater cities/homes, underground cities/homes, space stations, bases on the Moon, colonies on Mars and the moons of Jupiter and Saturn, giant airships and protected bunkers on Venus, etc.

     You do realize this is all extraordinarily unrealistic, though? There's nothing wrong with dreaming, but this is less a futuristic world and more a fantasy world.