Very valid. But that's more of a long term issue. If you want to starve the military, you need to starve the cash.
... that Russia has no prospects ("в безвыходном положении") and oil and gas industry in Russia will crater? Yes, it is as I have been saying. As for some countries not joining sanctions - doesn't much matter with news like I posted earlier about the ship insurers declaring that any ship entering Russian waters will have to pay them a premium of 3% to 5% of the cost of the ship (compared to, I think, 0.0025% prior to the announcement). Good luck shipping things to Russia.
I figured that out decades ago when libya was bombing airliners and doing terrorist stuff. Then I read that Qadaffi was the UN Human Rights Council Chairman, because I guess they have a rotating membership without regard to whether the person might be a serial murderer. Did not pass the straight face test with me. The l.e.d. light on my forehead starts flickering from red to yellow, red to yellow. Then red.
Russian airlines tried to get around sanctions by using middlemen. US has just put them under re-exportation sanctions, basically making anyone who sells them parts liable for sanctioning by the US. Russian airline industry is basically dead. By cannibalizing stolen planes they can limp for a little while but soon enough all flights, including internal ones, will end.
Russians will go back to the train, and that will take them one more step towards soviet era. Or they'll run planes until they fall out of the sky, which also will have a deleterious effect on the government! Assuming this works as you claim, that is. I'm reminded of US sanctions on companies dealing with Iran, and that didn't work all that well.
Interestingly enough Russian production of railroad cars has stopped as well. That's because all the cars were switched to so-called "cassette bearings" which are not produced in Russia and are under import sanctions. Changing the production will take a lot of time and money. Possible but will take years.
"Roller bearings are designed to last the life of the wheelset without additional lubrication or maintenance. On average, freight car wheelset service life is estimated at approximately 220 000 miles" So - a couple of years. Definitely not 80.
I was involved once with railway bogey construction and maintenance within a large multinational Co. (Not backyard). The amount of grease and filth in a maintenance workshop replacing traditional wheel bearings is huge. The type grease used is particularly black, very heavy and sticky. It makes sense to use cartridge bearings, saves on lots on labour costs.