Not only digital global currency but almost everything will be controlled by blockchain technology. That will be the new era of innovations. Blockchain technology is the latest controllable software for all our works, needs and information. One world currency will be soon applied throughout the world. Almost one forth has already accepted crypto as their regular currency.
There is no doubt that blockchain technology is taking every sector by storm and it is just about time before we started seeing it spread widely in usage and implementation. However, when it comes to having a global currency powered by blockchain which in this case we are talking about something created by the government, which obviously would be centralized, I really do not see how that would be plausible.
If we have to even consider a global currency powered by blockchain, I think bitcoin has already taken that spot as far as I am concerned, and every government worldwide, would practically just come up with the idea of integrating the blockchain technology into their system which would still be centralized and regulated as usual.