1. The USD will stay around forever as a measurement device.
Explain "measurement device". Anything can function as a "measurement device", USD, EUR, BTC, LTC, GOLD, etc. The distinctive aspect of USD is its current status as the global reserve currency. If by "measurement device" you mean this, I highly question it. USD, like any fiat currency, operates essentially in an experimental realm. But sure, it will probably always be possible to exchange goods and services for USD, just as with bitcoin.
You are mixing up the three uses of a currency:
1. As an investment instrument.
2. As a means of performing a transaction.
3. As a means of measurement.
Those things are independent of each other. US dollars are used as all three right now, but I suspect #'s 1 & 3 will decline over time. I don't see the world getting rid of usage #3 though. The most important thing about Bitcoin today is it's
value in US dollars. That's way everybody thinks of it. If I asked somebody how much something costs, and they replied "42.5 quatloos", virtually everybody would immediately translate that to US dollars in order to understand how much value that was. They can figure out how much of their savings this item would require, or how much work they would need to perform in order to earn it.
The world needs this regardless of what happens to the US dollar itself in the other categories.
Digital currencies, like? CBDC-USD? How is that different from banks and Paypal for low value transactions?
The US doesn't have a CBDC, and I suspect that project will never get off the ground. Non-government digital currencies will probably make CBDCs a moot point, I suspect.
As for the difference between a digital currency and PayPal/credit cards/banks:
1. A digital currency can provide
anonymous transfer, e.g. like physical cash (there are technical problems with things like Bitcoin for this because of chain analysis, but other digital currencies solve this problem in other ways, starting with simply legally promising to not divulge your privacy for any reason barring a government subpoena, e.g. like VPN providers work).
2. A good digital currency (I'm really trying to do this without self-referencing here
) will have an extremely low transaction fee. Say, $0.005 for instance.
3. A good digital currency will be extremely fast, on the order of 10ms per transaction, which is ~500x faster than today's credit cards and PayPal et. al.
4. A good digital currency will be suitable for high-scale realms like games, wherein they could use "real" external currency instead of internal currency because the transactions would be fast enough to keep up.
So yeah, I think "good digital currencies" are the wave of the future and will replace most of today's physical cash transactions and many of today's credit card transactions as well.
