Bitcoin, if it takes off at all as something more significant than Dutch tulips, will probably be relegated to commodity rather than currency, much as gold and silver are (with a little black market currency behavior on the side, just like gold).

As you point out, there's no obvious way to do fractional reserves, so it can't be used for debt-based capitalism unless someone comes up with a clever mechanism for that, something deeper than commodity-as-collateral. Avoiding the currency hazards of modern capitalism by not being able to perform the underlying operations of modern capitalism is kind of cheating. And if you can do lending on fractional reserves, how do you know the hazards of reserve currencies aren't a function of fractional reserves rather than a scalable money supply?