Ask HN: How would you force scarcity on a distributed DNS alternative?

I've been thinking a lot lately about the things that are broken with our current domain name system, and if there's any way we can build something that's truly decentralized.

The big thing I can't wrap my head around is how to build in some sort of scarcity without central control - how do we keep the botnets and domain squatters at bay?

A proof-of-work system similar to Bitcoin's is an interesting option, but it's weighted heavily towards the rich - is there anything better?