The ongoing pattern of capital flows is quite unusual. All emerging market economies finance American consumers who live beyond their means. This is clearly a misallocation of world saving that is unsustainable in the long run. The present paper uses the INGENUE2 worldwide growth model to shape the conjecture of a growth regime for the first half of this century. The engine of growth rests on demographic and technological forces tied up together in a catching up process involving very large countries. In this process, capital flows will substantiate an intergenerational saving transfer to the huge number of people who aspire to get access to Western standard of life. Two scenarios explore the consistency of this prospect: a baseline scenario with relatively conservative hypotheses and a fast-growth scenario in China and India. In both scenarios Western Europe and Japan appear to be structural capital exporters with appreciating real exchange rates. The US will progressively save more and recovers a strong foreign net position. Meanwhile no scenario will prevent world growth from decelerating with demographic trends.