The guy who started how stuff works had small book on the subject http://www.marshallbrain.com/manna1.htm.

But what really happens is that stuff finally becomes so cheap that people will stop buying more than they need of it and will presumably spend the rest of the money on things that are hard to make by robots: books, movies, professional services.

The they the robots can do that? Well then we will finally have obliterated the concept of scarcity, at which point the entire concept of economies are obsolete.