My answer is: no, not overpopulated. China’s pollution problem has likely peaked and India’s will likely in the next several years. There will be big issues in Africa. But keep in mind the African nations with the highest fertility and growth pains are some of the least densely populated in the world. Many countries can and will triple their populations and they’ll still be far less dense than Europe or South/East Asia.
Thing is, not every country can be equally dense. You can't have a huge and densly populated concentration of people in places like Africa, where half the continent is desert (see: the Sahara) and another huge part is jungle (like in the Congo).
