At this point it is a matter of which will last longer, the viability of the Russian economy/war machine or the will of the American people. Judging by current circumstances and current rhetoric from one side on the issue, I think it’s pretty clear the latter will collapse first, allowing Russia some sense of a partial victory.
This is always a super dumb strategy though because Russia probably can keep fighting on till the 2030s if they want. Keep in mind we stayed in Vietnam for 9 years after Gulf of Tonkin, 8 years after the Invasion of Iraq and its very possible we would have stayed there longer if we elected Hillary rather than Obama in 2008 despite the war being very unpopular. Keep in mind that Russia unlike the US is not a democracy so a war being unpopular is not enough to force the Russians to leave and the most likely replacements to Putin are those who are even more pro war than him so that solution was never realistic. Also Ukraine is right across the Russian Border unlike Iraq and Vietnam for us so its much easier for Russia to keep such a war going than it was for us thanks due to pure logistics so this strategy was always dumb.
The best hope to force Russia completely out of Ukraine would have been:
- For Ukrainian offenses to keep working as losing battles is worse for morale than a stalemate is
- For Belarus's government to fall as doing so would require Russia to divert troops to Belarus which would make Ukrainian offenses easier to execute
- For Russia's economy to have collapsed when we implemented the sanctions that we did. Doing so would have given us leverage to offer Russia a deal of them withdrawing from Ukraine in exchange for us dropping the sanctions.