>Russia can't sustain autarky on their own, and especially not with their demographics
Do you think Ukraine's demographics are doing any better?
I live in western Europe and every day I hear Ukrainian on the streets . Wherever you go in Europe, Germany, Luxembourg, Ireland, etc. it's full of Ukrainians (mostly women and youngsters). How do you think Ukraine's chances of success look like when all their women and youngsters are living abroad? Those are you future and they're not where they're needed most but building up other countries future and economies.
Ukraine is dying the slow death. If Russia doesn't do it, their demographics will. Even if they "win", the victory gained will be bombed out land hosting mostly scarred men and elderly pensioners. How is that a victory?