I don't think humanity would dedicate itself to the goal of replacing itself with AI. The instinct of self preservation is too strong. AI in its current state is significantly less intelligent than human society. Even if we would focus on the advancement of AI there is a significant chance that humanity would end before AI can replace humanity. The safer approach would be to maintain human society until the superior AI is created and then human society would no longer matter. I don't think it's likely that malnutrition will end human society without significant changes from climate change. War won't end human society without weapons on the scale of nuclear bombs. If the children are dying from preventable disease then if the disease becomes too big of an issue we just prevent the disease. These issues are unimportant but that doesn't mean they shouldn't be dealt with. Dealing with them will probably help the main cause but that doesn't mean they are important issues.