You can't argue with that; Within the country, the Russian Mir payment system is independent.
But after the normalization of relations with the United States and Europe, sooner or later the question will arise regarding the possibility of using Russian bank cards there, and the West will certainly not agree to operate Mir cards on its territory, subject to restrictions on the Visa and MasterCard payment systems in Russia.
Therefore, Visa and MasterCard cards will have to return to Russia with parallel access of the Mir system to the Western financial system, although this process will certainly not be simple and fast.