We are shifting from a world in which the US dollar is the reserve currency to a world where the financial system is based on SDRs: a basket of currencies + gold. In that basket of currencies we have the US dollar, the Yuan, the Euro, the JPY and others, it seems.
So I believe the US dollar will still be there but its role will be downgraded significantly.
It could crash overnight but the world economies are tied to it. So they need to gradually get away from it. That is what the Chinese, the Russian, the Japanese are doing: they sell US treasuries, and use other currencies to settle important payments (ex: oil).
It is obvious that the US government has been printing money since 01APR15 without having updated the debt ceiling.
Because of that, a government shutdown is likely at the end of Sep 15.
My point is that it would be extremely painful for the world to have a dollar crashing overnight. So countries are striving to prevent such a sudden change from happening on a single day. Nevertheless, it is obvious that the purchasing power of the US dollar is overvalued. So it is fair to say that the US dollar will be devalued: 25%, maybe 50%.
So what does it mean to NuBits?
It means that NBT could see its purchasing power divided by 2.
Would it a problem?
I would argue that it would not be a huge problem if it happens gradually.
If it happens overnight (it might be) it would be painful for people that put their savings into NBTs and the liquidity providers.
However I believe we must consider at the same time the possibility of a flash crash.
This is in fact the new type of crashes we have seen so far with the Aug crashes.
Those crashes were caused by rapid frequency trading (computer generated) with which humans cannot compete.
For that reason, I believe we should seriously consider the creation of a SDR-pegged or a basket of commodities-pegged NBT (let us call it SDR_NBT) just in case the US dollar is devalued suddenly.
Since such a sudden devaluation is less likely than a gradual devaluation, SDR_NBT should not be the main value proposition (the main product) of Nu but nevertheless it should be one of our products.
At the same time, as pointed out by @crypto_coiner, it would be a way to attract libertarians and pure bitcoiners to Nu.
Finally, some of the competition chooses SDR over the USD as you can see here for their peg.
To conclude, I think Nu should start a whole dedicated project into SDR_NBT.