Yea, it will be interesting when at some point every exchange converts to a new fork for some random coin and miners (pools) refuse, or vice versa. Right now, everyone just kinda goes along to get along, but at some point there will be a clash of civilizations. It's mostly exchanges that dictate everything right now since pool owners don't want to look like idiots having their clientele mining thin air that can't be cashed out.
This would imply the power to fork comes from the developer and exchanges, and miners come 3rd, which is basically the opposite of the Satoshi view. The Satoshi view seems to rely on the idea that there will be vastly more exchanges than mining pools, so whatever a particular exchange does has no influence on anything. Most altcoins are entirely centralized on one exchange. Bitcoin could be very centralized the same way in that regard having one dominant exchange in the US, and one in Europe or Hong Kong even years from now.
Interesting. Nxt has a trading exchange built into the block-chain, which is decentralised, so even if you can't convert NXT to fiat with an external exchange you will be able to buy assets on the internal exchange. Even for Bitcoin, I'd expect external exchanges to become less important over time as the currency becomes more self-sufficient.
