Here's a projection on Japan's population:
Japan's agency responsible for projecting population, the National Institute of Population and Social Security Research forecasts a stunning reduction of population to only 42.9 million residents in 2110. For every three Japanese residents today, there will be one in 2110 according to the National Institute of Population. If this projection is realized, Japan's population would drop to a level not seen since the middle 1890s.
The National Institute of Population projects a population loss to 97.0 million residents by 2050, for an annual population loss rate of 0.7 percent from 2015. By 2100, the population would fall to 49.6 million, for an annual loss rate of 1.3 percent. Over the 95 years from 2015, the annual population loss rate would accelerate from 0.4 percent annually to nearly 1.5 percent.
Now I know there's some folk who rather want humanity to die out (Jeremy Corbyn, for example) but Japan really does face a crisis because for much of the time between now and 2110 that country will be sustaining an ever bigger population of very old people with a smaller and smaller population of active working age people. This is essentially unsustainable. Unless, of course, you're like the UK and the USA and think immigration is rather a good idea.