The 21 million doesn't mean much really. The decimal point can be moved around. You would still need to go through a middle man to exchange btc to local currency for remittances. How exactly is btc going to lift the third world out of poverty? Many btc holders have already fallen victim to theft, and many more will in the future. People of the world won't suddenly turn to btc in the face of economic collapse.
Because the unbanked of the world will now be able to save their money. As the value of each bitcoin increases dramatically over the next few years, they will finally be able to accumulate wealth, free from corrupt government influences within their countries that would desire to confiscate it.
How can you possibly save wealth when there are savages everywhere that can rob and rape our family anytime? stability is needed first before third worlders can even hope to relax and acculumate wealth. Yes, BTC is great, but you are being delusional.