Yeah, if that happen. It will lead to economical imbalance in each and every country. Digital currency or fiat, we need multiple currencies for every country to categorise the country's power, wealth and economical status.

As quoted single currency makes a worse situation among the small countries which were already into economic fall. Always better for the grown countries and when it comes to growing country only very few overcome those issues and remain gets suffered in the middle.

If that will happen a lot of people will be fucked.

Let's pretend for a second that this is happening.

The biggest and powerful country will want to have the lead.

By the lead I mean she will try to approximate the value of the coin we all use.

1.00000000 coin everyone use is 100 USD.

One person who is working in the country I mentioned get a paycheck of 50.00000000 coins

One person who is working in the weakest country on the same position will get 5.00000000 coins

And now comes the best part.

prices for bread in the fist country 0.00500000 coins

and guess what the price will be for bread in the weakest country? 0.00520000 coins

This scenario is inspired by real life salary and prices, the only difference is that everyone will know it for sure as a lot of people are not good at conversions and if they are they don't care about prices in other countries.

Those exchangers could make a service to exchange real fiat money to digital account balance such as perfect money, paypal , or similiar. the exchanging business is not going to be closed, there many thing in this world that can be exchanged by fiat and not only to another currency but also digital balance which not everyone have

there would be a positive and negative thing when this happens, but I think there will be a lot more negative effects that will be caused. think about the positive effects that are generated when using one currency only maybe you do not need to do the conversion again, but there are a lot of negativ effects that can not be mentioned when this happens

Many other currencies invented by local elites. If they would use same currencie as whole world - they lose control over their country populace(slaves). Elites control money emission and always can make more money for themselves. Their currencies solve only problem of small community of people who controls authority.

Many of the causes of unrest in the world today are the result of unbalanced economic and social development
If monetary unity is reached, the imbalance can be solved to a certain extent.
I think it is conducive to social progress
But many liberals will stand up against it.