As a non Russian expat depending on the global financial system working, I can well imagine the pain, panic and indeed devastation of that being shut off.
Indeed some credible figures such as Fiona Hill are saying WW3 has already started.
https://en.m.wikipedia.org/wiki/Fiona_Hill_(presidential_advisor)
Whether that is true or not and whether Putin uses nukes or not, Putin sees these severe sanctions as an act of war. He probably has a point.
So Russia etc. will retaliate probably with cyber warfare perhaps messing up OUR access to the global financial system.
So back to the Russians abroad it seems to me that those that didn't bring in a pile of dollars or Euros are really up the proverbial creek without a paddle.
Who if anyone will help them?
Will the Russian government organize evacuation flights?