Your wrong.  Read up on the &quot;per capita&quot; effects of the Black Death which was linked to a temperary prosparity spike.<p>In modern times.<p>2) the effects of declining population reduce the number of non productive children and increases the number of working childless females which more than compensates. It also drastically reduces new infrastructure needs.<p>3) your math is way off. A 65 year old worker +25y would be unlikely to have two 90 year old parents let alone four 115 year old grand parents. They would also have  .7 children in the work force (65 - 25 ) = 40. So you don&#x27;t stack more than one generation pluss it&#x27;s 1.4 children per two parents.<p>This is also just starting Japan had positive population growth in 2010. And negative 0.7% in 2014.<p>The real issue for nations is needing positive GDP growth to keep up with external debt.