The US dollar is currently in decline, and along with it the supremacy of the USA as the global ruler. Combined China, Eu, Russia, and countries in the middle east have all began to move away from the dollar as the world reserve and are adopting others. While the dollar has a long history of being the world’s standard which is why many companies like MakerDao adopt it, the truth is that history cannot always tell us about the future. Many other currencies are appreciating against the dollar and have been for some time now, and with even more stimulus talks on the way this can only accelerate the process of the dethroning of the dollar as world reserve currency.
However, I do not believe that Dai should just jump to the next major currency like the euro or yuan if it hopes to be a truly global currency. The UN has been alluding to a currency based on an index of many major world currencies. For example, in such an index if a single countries currency depreciates due to excessive printing, then it will be offset by others appreciating thus evening out the index. If Dai were to create or track an index of many major currencies instead of just the dollar, then it would greatly add to the reliability and stability of the coin. Trust would be much stronger thus making adoption easier.
TLDR: A global coin should track an index of all currencies. This would greatly aid in stability, reliability, trust, and adoption of the coin.