I imagine when the Russian Army starts drafting the 30 year old professionals from the Western Regions, they will start to get some push back.
Up to now the state has been relying on Siberians and Central Asian Russians. Those guys are happy to be fed and fairly warm. Not so much with the intelligent folks from Moscow and St Petersburg.
How many body bags coming back to those cities will it take before people start getting angry.
I don’t know a lot of Russians, but the half dozen or so immigrants I have spoken to don’t care too much for Ukrainians..but to a person they said the war was not a good thing for Russia. They were more inclined to let the Russians in the East move into Russia proper, and then build a wall and have nothing more to do with Ukraine.
The problem comes with all of those pipelines flowing through Ukraine to southern Europe. When this is over, the Russians will want access to those markets.
Putin should simply end the war, resign and move to Switzerland with his wife and girlfriends, and let his facists underlings fight over control. We will witness Russia devolve into a bunch of religious states, constantly fighting with each other. But they won’t bother us.
Interesting thoughts, as to support for a full-up war there, it will likely depend on how it’s perceived - if it’s like Gulf War 1, then no problem - but if it’s like Iraq for 20 years, or even for 20 months, then, like you say, things will likely get nasty for Putin.