Ta all replys above – although economics matter, it doesn't matter too much. It's about people – Russia is already running out of people who are willing to die in Ukraine. I can't see it to last years.
I don't it's 1942 any more. Or even 1978. While it's possible to attempt it, it's not possible to frighten whole country any more. And even more importantly – it doesn't matter in which line you are in this war.