And the Euro. But yes, I think so. My only concern is that if it becomes a 1 trillion $ worth of economy, you'll be talking in very small decimals of Bitcoin. Everything will cost like 0.000000x Bitcoins. I think this will be a very poor UX for most people. Unless they give the smallest decimal another name (Bits, coins, nanocoins, whatever), and then everyone deals in nanocoins, rather than Bitcoins.
I wish the designer of Bitcoin would've thought about this before creating it. Maybe he just didn't think Bitcoin will become that popular, and become orders of magnitude more valuable than a dollar in a more distant future.
Actually Satoshi discusses this in his original paper many years back. People will just transact in a smaller unit, like micro bitcoins. The official client has the ability to display your balance in a smaller unit. It all works quite well.
I wish the designer of Bitcoin would've thought about this before creating it. Maybe he just didn't think Bitcoin will become that popular, and become orders of magnitude more valuable than a dollar in a more distant future.