The root cause is not a surge in deaths, but a slump in births. Across much of the world the fertility rate, the average number of births per woman, is collapsing.
If people or kids do not exist, then they cannot contribute to a nations economy. These will be huge effects by 2050 and even larger by 2100 and beyond. All of the forecasts that China and India will have economies many times larger than the USA will NOT happen. It is not just that the countries get old before they get rich, the countries economies shrivel up and shrink.
Japan is going from 122 million people today to about 100 million people in 2050-2056. By 2050, its population could fall below 100 million, of whom 38.8% will be 65 or older. 20 million of Japan's people are over 75 years old today and 37 million are over 65. Japan's per capita GDP is shrinking because the median age in Japan is 48.4 years old. About half of Japan's work force is over 50, which is when productivity starts dropping until they stop working.