Payment processors such as OKPay could support Nubits directly, just as it is supporting bitcoin, litecoin, and dogecoin now.
But that is not the best part, because such support is centralized. The better part is PerfectMoney, OKPay, Webmoney, Payeer, EgoPay etc all have APIs. If someone can provide simple code, business and grassroot individuals can easily become nubits liquidity providers, without anyone’s approval or interference, selling/buying NBT/USD, using these payment processors as backends so all fiats are off the server.