To begin with, the case you raise is quite improbable, and the consequences you foresee, too. Adopting Bitcoin fully would not solve Russia's problems as you have been told, but if Putin were to take a position like Bukele, Europe and the US would not ban Bitcoin as it would be shooting themselves in the foot. All this taking into account that apart from Bitcoin the adoption by some governments has already started. There is a list in the following thread:

Governments that accept Bitcoin for public services.

Some of those listed are local governments, but that's a start.