Massive improvements in standard of living are certainly conceivable. I can't speak for how the maths work out, but if you e.g. consider potential improvements that have no physical law preventing them:

    - Eliminating the requirement to work for a living
    - Eradicating disease (including mental health 
      and first-world diseases as obesity, RSI and diabetes)
    - Reducing health problems related to aging, increasing
      the number of healthy years of the population, 
      increasing life span
    - Eliminating aging altogether, enabling replacement of
      organs and body parts with improved artificial versions
    - Achieving sustainable energy production and transport
    - Eliminating the need to perform unwanted boring tasks
    - Fully-immersive virtual reality
    - Automating production of goods and services to such a
      degree that everyone in the world has access to the 
      same standard of living that the richest have today

The sky is the limit, so to speak. One obviously has to think outside the box of what the world looks like today, but the limits of economic growth are in physical terms far, far beyond where we are today. This is even without considering the very distant possibility of compelling space habitats that could support greater populations than Earth.