How many airplanes do they need to support just a bare bones internal network. My guess is maybe 100. If that is the case I could see them keeping the Airbus and Boeings going for another 10 years by cannibalism and an acceptance of a greatly reduced airworthiness standard ( i.e. If the engines start and some radios and instruments work they are good to go)
There will be lots of crashes but I think Russians are OK with that.