Consider this: before WWII, France controlled a vast number of colonies around the globe. They have since lost most of their territory, however their official name remains as French Republic and they're considered to be the same state as they were before.
Now let's take the situation in the USSR: in 1991 the 12 Soviet Republics split up and formed independent states, with Russia becoming the successor state to the USSR. Does this mean that the USSR merely changed it's name and lost a few territories? Or did the USSR completely cease to exist, while brand new states were created in it's territory?
I'm looking for a legal/historical answer, not a subjective one.