I think there is a more than 50% chance that Belarus is reintegrated in some form into Russia within this century. It's very clear that there is no plan for sovereignty post-Lukashenko and all of the opposition(like in Russia) has been exiled(so powerless). This is probably the 2nd biggest miss of EU foreign policy in the 21st century after Ukraine, they basically put Lukashenko in the same basket as Putin even though up until 2020 he did everything he could to maintain his sovereignty and got hit with horrible sanctions. But IMO it's too late now.
>Second, while Kaliningrad might be defensible (though I doubt that)
Russian military doctrine is kind of nebulous, but the one thing it is extremely clear on is that Kaliningrad will be defended using nuclear weapons. Exactly because it's basically not defensible using conventional means.