I suspect Russia will just keep slicing the sausage. Then take the western provinces and re install a puppet regime as was there before (like Belarus). If that turns out to be inadequate down the road, just take another slice or two down the road.

The USSR went partially this way in Finland: sliced off half the country, though they left the other half alone, on sufferance. I don’t think Putin would be satisfied with that: he’ll want another Yanukovych or Lukashenko.