I hope you have a good curveball.
What all of you are ignoring is the probability that the area of Siberia will break away and form multiple Federations.
There won’t be anything Putin can do about it. The region is so vast, all of the cities so small in population (with the average around 40,000 souls apiece), that the present Russian forces will be unable to do anything to restrain the region.
You can bet that the PRC - China - is watching carefully what Putin does about the breakup into smaller Federations.