Retailers aren't going to set prices for their goods that might fluctuate from $1 to $10 to $50 back to $1 within a week or so. It'd make it impossible to run a business.

What they ultimately want is to guarantee they're going to receive the equivalent of $X for every widget they sell, so they'll either have to declare that Y BTC = X USD regardless of market prices, or they'll have to accept whatever Y in BTC is equivalent to X USD on a given exchange on a given day -- which is essentially equivalent to doing business in USD directly, with BTC as just a weird payment mechanism.

Businesses are going to be hesitant to accept BTC for the same reason they don't tend to accept payment in kind -- you need dollars to pay taxes and wages.

Payment processors such as bitpay offer same-day bitcoin-to-fiat conversion and bank deposit with extremely low fees (0.1% - 1%), and are becoming the defacto standard. This is expected during the bootstrapping phase. Later, if bitcoin firmly establishes itself, merchants could choose to not convert directly to fiat.

Merchants would still need to convert to legal tender for payroll, rent, and taxes. Their income and expenses would still be more efficiently denominated in dollars (or the local equivalent). What is the expected draw for businesses to keep their operating funds in BTC as opposed to USD?

Did you read my post? Bitpay converts bitcoin to the fiat currency of your choice. It is hassle free and much cheaper than credit cards.