What stands out here, of course, is Asia. Some might be tempted to say this is dependent on how one defines "Christians." But the reality is, even if all Europeans, for example, were counted as non-Christians, Asia would still be significantly bigger: 4.3 billion non-Christians in Asia vs (under that scenario) 0.6 billion in Europe in 2050.
The fact of the matter is, Asia simply has the greatest concentration of people in the world. All strategies must wrestle with this reality. If we want to be out the Great Commission, the bulk of missionary resources really should be focused here.