And I think it would be foolish to say that the interaction between multiple decentralized, intrinsic-valueless currencies would not lead to at-least some novel economic effects.
At the current level, profound effects for the individual: Larger economic freedom, less cost, to move money over boarders and trade remotely. Possibility to save in money in stead of apartment. For submarkets: More effective blue markets, avoid absurd regulations and hide your money.
Great effects that comes when and if bitcoin takes a substantial part of the economy: It restricts governments to spend only taxes, taxes necessarily lower because people will hold fast to their money.
Keywords: Sound money, hideability, mobility. All new compared to fiats.