Exactly. If the business accepted Bitcoin exclusively, then there would probably be some fiat bills to pay. Therefore trading it for local currency would be necessary ar one point or another. I would think adjusting to prices to market value would be necessary to stay competitive. If coffee is 2000 sats then I might whip out my lightning wallet today and buy one. But if the price jumps 50% in two weeks and the coffee shop hasn't adjusted their proces then I'll more likely walk down the street and get a fiat coffee, holding on to my 2000 sats.