So Ukrainians should go and get Smolensk and de-Putinify the area, lol?
I know it sounds ridiculously premature, but I think the only thing worse than full defeat and occupation of Ukraine would be if Ukrainians win and go on a vengeful rampage into Russia, shooting retreating Russian soldiers in the back. Fingers crossed that this ends at Ukraine's borders, sooner rather than later.
Yes, the worst thing you can do to someone who has nuclear weapons is to put them in a situation where they have nothing left to lose. I'm sure a major reason for the sanctions on Putin-associates is to destabilise his allies sufficiently for them to want to remove him. It's difficult to imagine him backing down voluntarily or due to Western pressure.
I think a coup is getting more and more tempting for some of Putin's generals and/or oligarchs. Imagine the personal wealth and worldwide fame one could reap from this. Whoever knocks Putin off would be a hero in the West, and could get away with many things that would otherwise be heavily frowned up. Russian public opinion could be swayed too, what with the massive propaganda machine.