Can BTC replace fiat currency altogether in a country, if that is what they wanted?

7 transaction limit per second means, there is a limit on the amount of economic activity BTC can support.  Based on my calculations, BTC cannot replace FIAT in G20 countries (20 countries with the largest GDP).

It cannot do so for those countries with large populations either, regardless how rich/poor they are. (It goes without saying that it wont work if the infrastructure is not there which leaves out all the poor countries).

The largest country/economy where BTC would work may be those like Norway, Sweden.

Where this would make most sense? It would be for countries like Argentine, Ecuador, Cuba where the national currency is not really trustworthy and where they have a sufficient degree of computer/network infrastructure.