At present bitcoin has a way too small market cap anyway. With a total value of approximately $100-120M it is relatively insignificant and conversion to fiat currencies will be required. However, once it will have reached a more sizable amount (let say $10 Billion and above, $1T would be better), it will become a valid eCurrency with enough weight to be used as a bona fide medium of exchange. Current value of BTC would have to go up by 100-fold to do so though...
Let's be careful for what we wish for though, since at this stage governments will most likely start to show much more interest in BTC...