That sort of technology simply pales beyond reason compared to the technology we will possess in merely the next thousand years.
Zardoz - "What industry could justify the expense of the energy required to maintain a space mall?"
This will be the first of three nails in the coffin of Capitalism, and the money system itself:
Reliable fusion technology will provide humanity with unlimited free clean energy forever. Our fusion reactors will be able to exceed today's total world energy production by a factor of a million, and we'll power the entire planet using a few swimming-pool-sized loads of sea water a day. I predict this within the next fifty years.
"Economy, not technology would prevent it. What would they do to earn their keep?"
This is the second nail.
The very concept of "earning one's keep" will not exist for all that much longer. A fully-automated society will render the necessity for human labour obsolete. Every person on Earth will have unfettered access to anything and everything they want. I have no doubt that some humans will continue to engage in what we today consider "jobs", but it will be out of a desire to act or create, not necessity.
I predict this within one hundred years.
"Mining an asteroid made of cut diamonds in little, black felt boxes, gold doubloons and Dove Bars wouldn't keep it in business."
And this is the third.
Replicator technology will allow us to reconfigure matter on a subatomic level, providing us with an unlimited supply of any conceivable substance. Humans, long before this point, will have virtually outgrown what is one of if not *the* greatest hindrance towards a qualitative transformation of the nature of our species: the ancient problem of finite resources. However, replicator technology will allow us to surpass merely *virtually* solving this problem, and actually solve it entirely.
Given the exponential advancement of technology, I predict this within two hundred years.