5 minutes of thinking yielded only one "next cell phone" candidate: an education system that actually works.

Actually, I think cell phones will do that. They don't yet, but as smartphones get cheaper and infrastructure improves, internet access will become a human universal; and at the same time, there are projects like Khan Academy that turn internet access into education. There is still lots of work to be done - the phones themselves are still too expensive, a lot of countries don't have affordable wireless internet service fast enough for educational videos, and there aren't enough good videos or translations into enough languages. These developments are probably inevitable, but they can also be sped up.