No merchant is going to hold bitUSD for some time.
Look at the cycle of bitcoin. Right now, after years merchants accept bitcoin only to exchange it for fiat. I believe the next phase will be that some of these companies will start to hold parts of bitcoin.
Put simply all we need now is a stable wallet and a big ass buy wall for "input your market pegged asset here". A buy wall for bitUSD at say .95 would allow merchants to start accepting bitUSD without needing to understand the technology. It would promote and expand merchants market to bitUSD users. After some time merchants if they have had a positive experience will naturally want to hold at least some bitUSD, so that they can keep the full value.