(Disclaimer: geopolitics and IR are not my field, and I don't really know what I'm talking about.)
I was trying to picture a scenario where Putin "wins" this in a way that he considers an actual victory, and I couldn't come up with one. Sanctions are not going to stop any time soon, Ukraine is unlikely to give up, Russia can't hold Ukrainian territory long-term... I just can't see a win for Putin, no matter what happens.
What I can see happening is the Russian elites deciding that they've had enough of the old man, and they just want to go back to "normal". With him out of the picture, Russia has an "out" and I'd imagine the West would be willing to go down that road instead of prolonging the conflict.
The part that sucks is that, even if there is a regime change in Russia in the near future, millions of lives have already been turned upside down in Ukraine. Telling them to "hold on a little longer" is a slap in the face, but that seems to be the West's strategy right now.