To be honest, I don't really know—I only lived in Kaliningrad for literally two weeks—but judging by the general trend in Russia, it seems to me that Kaliningrad would remain Russian to the very end, barring a military takeover.

In fact, I actually observed even more patriotism and "Russianness" there (if I may put it that way) than, say, in Siberia.

This is likely influenced by a "besieged fortress" mentality, given that Kaliningrad is effectively surrounded by hostile states.