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?
You are right, bitcoin will be out of circulation. Scarcity is one of the reason why bitcoin is so high. 21 million supply minus coin out of circulation plus high demand means price rocket. Unfortunately there is no way to recover it, you need billions of dollars just to try to hack into the system and there is no guarantee that you can penetrate the system.