Yes, I think that's how it could go down. Or Yen-guy and USD-guy could exchange currency directly, or they could do it hawala-style indirectly (for example: Yen-guy could hand out yen to anyone wandering into his Tokyo shop with USD-guy coins, and then USD-guy, to settle his bills with Yen-guy, can fly in and visit Yen-guy with a case of wine which Yen-guy can drink or sell).
The bitcoins that I had set aside for a Cryonics contest two years ago (and were unredeemed) are suddenly worth a lot more.
Details: I had added 10 bitcoins to get things started, and there were 4.75 worth of additional donations. These were partially lost when the hosted online wallet that I was using (MyBitcoin) was hacked, but 49% was recovered. As of today, after refunding part of the donated money, it is now worth 5.2675. I will be adding from my personal store to bring it up to an even 5.5. At $140 per coin, the new total is $770.
I've decided to follow the buy-and-hold strategy for at least another year, since it worked so well. I don't have exact details on what I'll do with it, but it will not be converted or spent for at least one year, and will eventually be used for promoting cryonics in some way.
Some things I have in mind if it gets big include:
Contributions can be made to:
1Jdn36JUwvJdr3Qiie4aAseFdcoTsND9Qo
(Updated, since the previous address was attached to my personal wallet on an outdated client, which was causing money to be moved out of it by accident. The above is a brainwallet with a reasonably secure passphrase, generated using Blockchain.info.)