I mentioned this elsewhere, but encryption is a great example: other than the breakthrough of another sort (like quantum computing), we can easily come up with a key size that is exponentially harder to compute solutions for compared to computing power increases we can achieve. In a 100, 1000 or a million years.

What if the problems we need to tackle are of a similar complexity? Do we ever get there?

We are all holding our breath for both fusion and quantum computing, and while we know they are theoretically possible, will we ever make them practical?