If bitcoin gets accepted worldwide enough there would be no point to convert them in FIAT money. It would be just another currency. And at the current BTC situation I don't think that this would massively happen.
Acceptance happens through business. What is behind USD's wide acceptance ? Their businesses across the globe. This Amazon Ebay like companies are behind USD's popularity. So to make BTC popular, we need BTC oriented companies.
This is what overstock and tiger direct are already doing, no way to be sure, but I have not seen a big price impact as a result...
USD 1000 to USD 500 ...and u r saying no price impact ?