GDP per capita for those remaining indivuduals would only go up if those who disappeard were somehow destroying GDP per capita for those who remained. How is

GDP per capita for those remaining indivuduals would only go up if those who disappeard were somehow destroying GDP per capita for those who remained. How is that possible in any reasonable state of the world ? As long as those who disappeared where on average non zero marginal product, then their disappearance would lower GDP per capita for the remaining ones