You're describing how BTC looks today. The vision is that if liquidity is high (billions of transactions a day), then BTC could in theory replace all mediums of exchange between currencies. Today, for example, the dollar can be hedged because the price of oil, and vice versa. So we don't always get a true value of the dollar. (it's way more complicated than that, just trying to simplify) Additionally, using BTC massive lowers the barrier to exchange money (i.e. you don't need a bank). Banks make a lot of money (ever seen a "transaction fee"?) by simply moving money around.