Yeah, that's true and it's actually one of the few things that is inevitable, whether we like it or not , a certain number of Bitcoin owners are actually going to end up leaving this world with their key remaining unknown to anyone, even their love one, but I feel this is supposed to be a matter of who's going fall under this category, well I know for sure after all this exposure to this much knowledge, I will definitely find a way to let my love ones or even my spouse know about the my holdings or if that's too wild, I think setting up a means of which they can actually get hold of my key and Bitcoin when mr.death eventually comes knocking.
Do you know what most people who are holding bitcoin are doing or will most probably do? All of them know that they will transfer their private keys to their loved ones when they are near to death but no one will let the keys be transferred ahead of time. Since the death time of everyone is unknown, there may be many who die because of an accident or on the spot death and they would not even get the time to give the private keys to their remaining.
Since bitcoin is very new and only the first generation is using it, so we do not come across such cases but after more than 10 to 20 years, a lot of bitcoins will be lost as the current holders of bitcoin wouldn't be alive and they have not transferred the wealth to their near and dear ones.
Agree with you this makes perfect sense and will probably be one of the problems of every bitcoin holder, we know that we will not live forever in the world, while something in the future is always unpredictable, one of which anyone will never know when they will die, while on the other hand they have promised themselves that one day they have to transfer the key to someone special in their life such as their own wife. Basically the facts that will happen will not always match what we plan, okay maybe they plan that they have to give the key near the time of death, but it will not always be like that, maybe you think that you will die while in the hospital in the treatment phase and at that time you will whisper your bitcoin secret key to your wife, this plan looks very neat. On the other hand, you will never know under what circumstances you will die, it is possible and very likely that you will die in an accident or any circumstances that do not allow you to get time to share the secret key with others, this makes perfect sense.
As you said "Many bitcoins will be lost because the holder is no longer alive" And in my opinion one of the alternatives that can be done is that I will give the secret key to my wife from now on, no problem and I have indeed said a very important short message to her, none other than this as an action to minimize things that cannot be avoided such as death. I will write the private key on a piece of paper and keep it in the most secure place along with telling my wife that if one day I die then open the box, it is an inheritance from me for our children someday.