Ok, but I think the point is clear. USD has value because U.S. government said so and people trust that government, and Bitcoin has value because some people trust the Bitcoin network as the "currency issuer".
If we imagine a scenario, where a majority of businesses will accept bitcoins, and people will be able to buy bitcoins and use either dollars or btc for payments, and both methods will be legal, we will see that dollar doesn't have any more "intrinsic value" (whatever that means) as bitcoin. It will be just two competing payment systems with different attributes.
Right, the trust in the future spending power makes a currency not only a medium of exchange, but a medium of store.
It seems that as far as alternative currencies are concerned, altcoins have a better chance of being spread. What's to prevent Amazon from coming up with AmazonCoin, pre-mining an entire AmazonCoin set for themselves, and then offer this altcoin with a liquidity guarantee on largest retail site. Nothing to prevent them from accepting BTC, but I think any US retailer would be prone to quickly trade in BTC for USD after the transaction is completed, as there's volatility risk, and payments to merchants and the tax man are due in USD anyways.
If we imagine a scenario, where a majority of businesses will accept bitcoins, and people will be able to buy bitcoins and use either dollars or btc for payments, and both methods will be legal, we will see that dollar doesn't have any more "intrinsic value" (whatever that means) as bitcoin. It will be just two competing payment systems with different attributes.