[wcoenen]

Instead of trying to come up with a way to measure demand, you could just have each block contain a vote for what the mining reward should be. When the difficulty is adjusted, the block reward could be updated to the median of the votes.

The same could be done for other parameters (like the targeted time between blocks) or maybe even for more complicated things, like what kind of digital signature algorithms are acceptable.

I'd call it "votecoin".