However, I wouldn't value a piece of paper "I owe you 10 bitcoin" as much, as 10 real bitcoins in my wallet !
It is like paper gold and physical gold, except for the problems of actual physical gold (securing it and so on).
I would rather think that bitcoin is especially suited NOT to do fractional banking with. There's no difference between a bank account and a bitcoin address. So nobody can mess with your coins and lend them out multiple times.
Surely there will be fractional banking with bitcoins, just as there was with dollars when these were officially backed by gold. An account in a "bitcoin bank" is only an entry in the bank's ledger. People do not need to see "their" bitcoins in the bank's "vault", they only need to trust that the bank will hand them over if and when they decide to withdraw. Bank clients gamble on that trust, even when they know that the sum of all bank accounts is more than what the bank actually owns. Meanwhile they can pay with those virtual bitcoins, that exist only on the bank's ledger, just as if they were actual ones on the blockchain.
MtGOX was an example of that. People were buying with real dollars, at or above market price, some 600 k bitcoins that existed only in MtGOX's database. Even after people realized that MtGOX was insolvent, some managed to sell their "GOXcoins" on other markets, for way more than their actual worth in real bitcoins.
[The Linden dollar] didn't turn out to be a monetary asset, right ? It was at most a valued collectable. I have no knowledge of people paying their grocery shoppings with Second Life Dollars. And as long as we can't with bitcoin, it will not be money either. But the idea is that one day, we will. If not, then bitcoin Q will be very low.
I don't think you need universal adoption to use that formula. Not everyone in the world accepts euros, or Brazilian reals. As long as the currency is accepted and fungible in
some market, the formula should hold.
We are those potential seigneurs. There's nothing wrong with that, I' d think.
The seigneurs may think so, but the rest of the people will not like the idea.
That is why every minimally functioning government will stamp out private currencies: even if they succeed (or, rather, to the extent that they succeed), they are essentially scams, that take billions or trillions of wealth from the users and transfer them to the seigneurs' pockets. It is hard to tell precisely when and how the users lose wealth, but the losses are real because they must add up to the seigneur's gains.
That, by the way, is the motivation for the existence of so many altcoins. "Why should I use bitcoin, and let Satoshi & friends get filthy rich at my expense, when I can create an altcoin, and hopefully get filthy rich at its users' expense?"
The US government forcibly destroyed the Liberty Dollar partly for that reason, and acted to ensure that game currencies such as Linden Dollars were not widely used outside of the gaming context. China and other countries banned bitcoin from the mainstream economy, for that same reason.
(Indeed, the thing that still puzzles me most about bitcoin is why the governments of the US and their
poodles close allies are so warm about it --- even though the most enthusiastic bitcoiners openly claim that its goal is to weaken the US government's control of the economy and render the dollar worthless.)