> It's an horrific idea, but what if Russia does not stop after invading Ukraine?
This is a very good question.
My guess is there will be a period of consolidation (one year, maybe two) and then the next target will be set, either Belarus will be pulled back in or Kaliningrad will be re-connected to the mothership. The fact that it isn't is a serious issue for Russia, they have to cross NATO controlled territory to get to one of their more important bases.