It is true that if B&C was built on top of Nu, we could use NuBits as the transaction fee. This would create new demand for NuBits in order to use them for the exchange. It would also allow NuBits to be destroyed regularly by using them as the fee, creating a natural way to shrink the supply besides variable transaction fees.
I have also suggested building in user created assets on the Nu blockchain (See my post above on that). This would allow NuBits to be destroyed as a fee for creating assets. NuBits could also be destroyed through asset transactions, dividends and motion voting. All great services that could be added to Nu to help naturally reduce the supply.
The problem though comes because of scalability issues, too many business models on top of one blockchain leading to lack of consensus and possible forks. This is why @JordanLee embraces the peershares philosophy of separate blockchains dedicated to separate services, rather than the one blockchain rules them all philosophy.
Still it would be great if we could find new services that actually aligned with Nuâs existing business model that allowed for NuBits to naturally be destroyed.