What happened to Prussia?

Prussia started off as a small puppet state of the Polish-Lithuanian Commonwealth in 1525 until it broke free, annexed Poland and finally became a dominant force in the newly formed German Empire in 1871. After WW1, Prussia became an exclave called East Prussia but following WW2, Prussia was abolished and made part of the Soviet Union in 1947. When the Soviet Union collapsed in 1991, neither Germany, Poland or Lithuania were interested in annexing it and Kaliningrad (as it is now called) has been an exclave of Russia ever since.