IF that happens. There is still a chicken-egg dynamic at play (businesses don't plan on holding BTC and no one seems to reliably hedge against USDBTC volatility at a scale that justifies using it for business. Expenses are still in dollars so revenue needs to reliably exceed expenses. If that means grossly unfavorable prices, people will just convert BTC to USD first.)
You clearly haven't bothered to learn about their service:
"To calculate the exchange rate for US Dollars, we pull up-to-the-minute BID prices from three exchanges. We take the 2 that are closest together and toss out the third, so that a bad feed from one exchange will not affect our calculation. Of the 2 rates that remain, Bit-Pay uses the highest BID price as our exchange rate. "
Companies don't end up changing prices every minute. Gas stations, for example, are prohibited from changing prices too frequently in many states.
A proper solution has to provide more than one minute of price stability. BitPay doesn't provide longer term price stability.
