As you have learned so far one of the most common and popular conversions currencies is the USD. It is used for almost anything. Now most of the bitcoins are converted from BTC to USD, but that doesn’t mean that it has to be like that. There are other rate you can consider.
What other currency can you change it to?
Well if you’re using a converter online they have different options where you can choose to change the currency. If you live in a remote country where bitcoins aren’t popular they will still give you the amount in that currency. So it is available for conversion in any currency.
Why are other currencies not used?
Now as you know BTC to USD is much, much popular than any other thing, therefore the use of other countries currencies get demoted. And they aren’t used that much either as because Bitcoins aren’t very popular. If you take Sri Lanka for example most of them have never heard of Bitcoins, so there is no possible way that the use of Bitcoins would exist here. As to it is converted in USD. If people aren’t going to be familiar with it why change the conversion methods. It makes no sense.
What happens if any other currency is used?
This won’t be much of a big deal as it is just a conversion you can convert back. If people start to use a different currency to convert then people would have to adapt. Or they would have to keep converting how they were doing before, simple as that.