Russia created its own system similar to Visa/MasterCard after the first round of sanctions in 2014

https://en.m.wikipedia.org/wiki/Mir_(payment_system)

Other networks. International ones like Visa or American Express, or national ones like Carte Bleue, Bancontact, etc.

Visa is blocking them too

I interpreted the parent comment as how to react if the Mastercard network goes down worldwide when Russia retaliates by trying to hack them.

Payments networks inside Russia is another matter altogether, but I assume like most countries they also have a local card network (Edit: found it, it's called Mir[0]). In that case, the issue will arise only when trying to use russian cards outside Russia.

[0] https://en.m.wikipedia.org/wiki/Mir_(payment_system)

Cash is King! You need functioning internet and banks to accept crypto.

Being pedantic but you only need banks to convert crypto to fiat and via versa. But given they context here I concede the point.

Cash is also subject to hyper inflation which is likely given the rapid drop in the value of their currency, making it a poor store of value.