If some people has lots of bitcoin in their offline wallets and they die or lose memory.
Then those coins will be out of circulation right? Or is there any way to recover them?
That depends on where is your private key and seed words, this is why it has been recommended many times in the forum that you should keep a copy of your seed words and private key, if you only lose your memory you will be able to access your coins that way but if you die you need to leave instructions to your family members about how to retrieve those coins.