It's time for people to stop using this awkward and outdated Charter terminology. It is a deeply conservative, mesmerizing use of language. They forget that there is nothing permanent under the sun, including permanent members. Britain is even ceding most of its powers over Scotland to a separate Scottish parliament. Clearly there is nothing permanent here.
China is also a case study of impermanence.
Then, in 1971, Beijing got the seat back again. The most recent drama of impermance played at the UN in 1991. Today's Russia is not a superpower, militarily or economically. Its economy is in dire straits and its huge military apparatus is in a state of collapse. Breakaway movements like Chechnya gnaw at its territory.