Sure - if they have some bank that isn't sanctioned (AFAIK there are 0 domestic banks not sanctioned) - or money already outside of Russia (only the rich, and most of the mega rich are sanctioned individually).
you know wrong
Unfortunately no. Gazprombank, Raiffeisenbank and Rosselkhozbank are partially sanctioned but operational - they allow to do swift transfers, their own native transfers to select post-soviet countries and their unionpay cards work relatively well outside of russia.
And where will they convert their rubels to USD?
Probably lots of countries and people still doing business (and trading) in russia who needs RUB. So p2p crypto exchange or cash