Millions of bitcoins are considered lost. Who will find them?
It is still a hard things to do for nowadays technology, to recover coins from someone wallet that is already dead. People that can find this lost bitcoins are, :
1. Someone with the credential info of the wallet.
2. Someone with a traces or clue that is enough to know the credential info of the wallet.
3. Someone with enough power and technology to brute force the wallet. And to make it done in a short time.
As i answer that 3 on top, i guess the investor would not want to share anything about their investment to others so no 1 and 2 is a no, and there are no technology can do a bruteforce in a short time for nowadays technology. So, the answer is, no one will ever find it.
That is why, to make things better, if you hold on to bitcoin, you need a most trustable person to inherit your coins after you pass away. I suggest make a inheritance about the wallet info and inherit it to someone, your wife, son, daughter, etc. It is the right thing to do, because your bitcoin can be a useful thing for the live, and it will also help bitcoin to live as it will not increase the number of lost bitcoin.