Dear Rk Naresh thanks for yet another one-million dollar question!! I think the pessimistic answer we'll keep redefining our key concepts (development, conservation, development and sustainability) in order to make the real question (your question) go away, until all the major players will agree that it has been answered in an objective and optimal way (and not by what I have described above). This is the pessimistic way.
I think there may be an optimistic way. We take a stand and say that for the next two hundred years we'll focus on restoration of sustainability and in general of the planet, and not on getting rich. This may bring some results for the long-term good of humanity, don't you think?