I think BTC is going to rise its value if it's denominated in USD. If it's denominated for example, in gold, probably it's going to drop in value.
I believe neither Bitcoins, dollars or gold have any "intrisic value". I think that none of them are well suited to be money. BTC and gold are deflationary (better for the saver) while national currencies (I'm including the euro here) are inflationary. In the past, gold didn't has to be deflationary if the production of gold was greater than the "economic growth". None of them can reach price stability.
Would you want a "price stable" currency versus a deflationary currency? How would you achieve this stability of price? How do you determine if there is too much of a supply or there should be increase in the supply?
With Ripple (and LETS), there's no limit to supply. The stable prices just depend on the unit of account in transactions. There are other claims for currencies that allow price stability.
1) Gesell said that central banks can't achieve stable prices because they can't control the velocity of circulation. He said it can be controlled (and stimulate it) using demurrage. Then it would be easier to for the central bank to correct the changes in prices by issuing more money (giving them debt free to the government) or by letting it disappear with the demurrage. I can't recall it, but maybe the government was responsible to give money back to the central bank for destruction in deflationary times.
2) The terra (
http://www.terratrc.org/) has demurrage too and is backed by a basket of commodities.
3) In a Ripple-like system you could create a currency dependent of the price of a basket of commodities. Since ripple doesn't need to store the commodities to "back the debts" and the currency is just a unit, the basket can be composed of any number of different commodities. However you measure inflation, you can use that to define a currency in a Ripple or LETS system.
I personally like the third solution.