Quantum computing. Actual hardware is shipping now. This stuff is akin to what was possible with early computers, limited in what it can do. It's exactly the kind of thing that, if it can ride another Moore's law of expoential growth, will lead to crazy changes in the future.
For one thing, it's very likely that quantum computing will be able to break all previous forms of encryption. Quantum crypto will be a big deal in the near future as well.
H.