This is why Bitcoin, Litecoin, Ether are on top, but other coins will rise as well. This is what we're seeing today - Crypto scaling horizontally to deal with scaling issues and transaction fees.
I don't see any government making a crypto the 'default transaction mechanism' as it would work against the government itself. Being able to control your currency, and print more when need be is what allows a country to manage their long term debt and fund things like large infrastructure projects (or wars etc..)
Crypto is just like gold, just better at storing value than gold in every way - so people are moving over to it. Just as gold doesn't replace cash and credit cards - don't expect crypto to either.