That will never happen.
Retailers are in the business of selling goods, NOT speculating on whether btc is going to go up or down.
I think you're missing the point though. BTC is supposed to be a currency not a speculative investment. Is Apple "speculating" on the dollar by keeping billions of USD on hand? If businesses were using BTC for more than just accepting purchases, it would be a little different. Think about if they could actually use the BTC they collect from sales to purchase more goods, pay staff, pay rent for offices, pay their web hosting costs, etc...
International companies keep the majority of their cash in their home country's currency as well.
They'll keep an amount of foreign currency that's sufficient to do business (to pay expenses, etc), but will usually convert the rest into their home currency.
So basically they're treating btc as a highly volatile foreign currency that they accept for payment, but have no use for when it comes to paying expenses, so the only thing that makes sense is to exchange it for USD in a short amount of time.
Holding BTC is GAMBLING. It could go up/down 10 - 20% (or more) in a day.