Earlier quoted context omitted.
>The US dollar hasn't been backed by anything since 1971 and is still ticking strong. I think you might be overstating. The US dollar is not backed by an asset because it is an asset . At this point, the dollar is backed by the government, the government's authority, its military power, and the future value of its debt. That is not gold, but it is not nothing either.
By the same token, cryptocurrencies are backed by the computing networks underlying them, the potential future usage of these computing networks, and by your ability to buy guns, drugs, and hacks with them. This is also not gold (although you can buy gold-backed cryptocurrency: see Digix), but not nothing either. That's why cryptocurrency evangelists harp on adoption and new use-cases: the value of any currency is pr…
What sets that exchange rate is demand for bitcoins, and demand for bitcoins would be equivalent to what you can buy only with bitcoins. So, I guess in a way that tracks to exactly what you describe. The part that doesn't track is the profit potential. Currency speculation is an interesting thing, but it doesn't usually track with the use of a currency.
I am pretty bearish on the long term viability for cryptocurrency growth, though. I expect transact in bitcoins about as often as I transact in any other currency...almost never. There are no wages, products, services, or geographic areas that require the use of bitcoin.