China cannot possibly mobilize the way the US can...no other country in the world can for that matter. China might always have a "commercial interest" in African countries, but they are LONG way off bumping the US out of anywhere...shit they cant even get us out of their own swimming pool. And they have far too many problems at home to even begin thinking about a new era of African colonization, they would get their asses handed to them real quick, by Africans (if the 4 or so US Aircraft carriers between the Eastern Pacific and the Indian Ocean don't "politely" ask them to turn around beforehand.
Africa is a depopulation program: No matter what their leaders do, the continent as a whole continues to suffer out of primeval self-interest of those in positions of power failing to bring their countries out of centuries of infighting, and into cooperation, stability, and prosperity. Until African leaders eschew corruption, or until their consituents hold them accountable, they will as a continent more or less, continue to suffer not because of what you perceive as "depopulation programs" but out of ineptitude.