I can only speak for myself, but as it has been identified to pose a (financial) risk for liquidity providers to offer NBT/BTC trading pairs, Nu has a financial incentive to phase them out.
With the liquidity providing becoming decentralized and not being provided by shareholders the financial risk is being delegated to the new decentralized liquidity providers.
But indirectly this still poses a financial risk for Nu, there’s just a layer in between. I think so because the liquidity providers either need compensation for the risk (which needs to be paid by a grant) or they will pull walls in case of highly fluctuating markets, bringing the peg in danger.
So it’s in the best interest of Nu to discontinue other pairs than NBT/fiat.
NBT/BTC is still available as long as fiat/BTC is available next to NBT/fiat.
But those who want to trade NBT/BTC then need to take the extra step on own risk.
I can only recommend to stop NBT/BTC as soon as possible.
Currently it’s still needed due to lacking NBT adoption.
Paying for the higher price of offering NBT/BTC (higher compared to NBT/fiat) is paying for advertizing NBT.