Because Germany has no interest in Kaliningrad and Poland has no (or a very weak) claim, I'd say should it come to that, Kaliningrad will be demilitarized and then "given back" to Russia.

And the argument was about nukes, in the event NATO invades Kaliningrad because of missle sites, not if it should or would.

Funnily the staunchest supporters of Putin in Germany (Nazis) would also be the only ones who would like to have Königsberg back.