I follow your reasoning up to an extent here. My main problem is that you're making a lot of assumptions about Russia's economy that we really don't have data on. What you mention about casualty rates is also predicated on the fact that they will continue at this rate which we don't have any guarantee of.

So, first, Russia has not been squeezed by sanctions at all. They have replaced European business very quickly and reports find that Wagner profits in Africa have also added to the confusion about how well or poorly Russia is doing.

Furthermore, Russia does not need to last three more years. As I wrote that is what Western intelligence has suggested. For all we know, this intelligence could be predicated on factors that you failed to mention, i.e. the health of Putin, etc.

Nonetheless, it is much more reasonable to presume that Russia would fight to outlast Western support for Ukraine rather than to defeat anyone at this given moment because the mentioned casualty rates -- something I state in the article above.

All in all, there are many factors at play so overt speculation can only be right to a certain extent. We're talking in terms of probability. Some humility is warranted then.