At this point, Russia needs to be broken and has its proverbial teeth kicked in to the point where it's shitting molars.
They won't ever stop trying to expand. They want Europe under their thumb again, like in the ol' Soviet/Russian Empire days, as being expansionist is part of what they are as a nation.
They need to be broken to stop this from ever happening again, and if that means that the country finally Balkanizes into different states, all the better.
The only problem is the elephant in the room: nukes.
Conventionally, they're fucked. But the "nuclear question" is what it comes down to.
Putin is deluded and desperate enough to try anything at this point, including a 'tactical' nuclear response/thuggery -- even though Russia's nuclear infrastructure is completely decayed, all it takes is one missile to be working. One.
Basically, our best hope is if one of his generals finally sees what an unhinged lunatic he has become and puts a 7.62mm in the back of his head one day, while he's eating breakfast or shitting on the golden "porcelain throne" he thinks he possesses.
If Putin does try to annex or invade Moldova, Romania is going to step in. And when Romania steps in, it'll drag NATO in one way or another.