Well the Ruble is now dead
It would be the ultimate irony they'd start using Hryvnia.
The ultimate irony is already here, every Russian citizen is cursing the US and desperately trying to get dollars for rubles.
I find all the "bitcoin saves Russia" part a highly overrated dream of the (imho) new bitcoiners.
The thing is that, as you said, nobody sane would sell bitcoin for rubles. And those who really have money, they have euro, dollars, maybe yuans too, probably also not under their name. So whether they change into bitcoin or not is completely unrelated to the sanctions.
Of course, Bitcoin or crypto won't save Russia ever!
It can save the personal finances of poeple in Russia, that's a given but it can't force foreign companies to deal with Russian companies so it does zero.
TSMC could fr example still sell chips to Russia and get paid via SWIFT, but it decides not to, and not offering them oil or gold or coins or anything else will change this.
But of course, poeple here have a biased vision, they think cryptos are the solution to everything, it will be another chapter in the revelation that it's not. Personal finances are one thing, global trade is a different thing, and when I see poeple who invest 90% of their money in shitcoins giving advice on how a country should run makes me laugh.
This is from CZ:
Does Russia want to use crypto? No, it devalues the ruble. Russians converting from ruble to crypto weakens the ruble, which weakens Russia’s powers
Doesn't it make sense?
Why would Russia switch to crypto when that means actually importing foreign currency and destroying your own economy?
This si how the Weimar Republic got $%$# it had to buy dollars with useless paper money, Russia will have to do the same, it will have to buy an asset that is in the best scenario having a constant price in USD with a evaluating ruble. It's economic suicide.