What this war in Ukraine is showing is that Russia military rank is overestimated.
The back of any war machine is the economy. With the expected drop of 15% on GDP, Russia will be behind Spain in economic terms.
Russia simple doesn't have the capacity to support a prolonged war. Not even in Ukraine.
If Russia doesn't make a deal soon, his negotiation power will disappear soon.
As the war continues, casualties increase, desertions augment, economic sanctions ruin the already poor Russian standard of living and its war machine breaks down.
We could face a new Afghanistan, with the West supporting resistance on a full occupied Ukraine.
What is in question is if Russia can indeed occupy the all Ukraine.