The long-term effects of the demographic divide are apparent when we look at population projections for these two countries. Today, both countries have roughly the same population size. But by 2050, Niger is projected to have 49 million more people, increasing their current population nearly four times to 65 million. The Netherlands increases by just 1 million to 18 million, with much of that growth due to immigration.
To be sure, if you live in a country like Niger, your only hope for a better life may be to migrate someplace else, which is why Netherlands' growth, like in so many rich countries, will come from immigration. The world may be demographically divided, but we are actually all in this together.