Do not forget that a significant part of Prussia is actually Russian today, including the old and quite important city of Königsberg (Kaliningrad now). It is that little enclave between Lithuania and Poland.

It is actually a quite interesting case you know, as all non-EU citizens need a visa to enter the EU, but that forces the Kaliningraders (or what you would call them) to get a visa to enter Russia proper, unless they fly or sail.

In time it simply can't sustain that I think, and it might splinter off completely.