First, there is no way to technically distinguish between lost coins and purposefully unmoved coins.
They both are the same and it is not reasonable to make people move their coins every so often in
order to prove that they still have control. If in the event, a protocol change is proposed that users
will need to transfer their coins to "safer addresses" that is done as a security measure, not just so
that the devs/miners know "we can't take them back" from them
Again if 10 years is too little, what about 25 or 50 years?
Other than that, what about adding some parameter which would basically say that the coins from this wallet shouldn't be moved under any circumstances with default being set to donating them after some period. That might work very much like organ donation, and the way voluntary consent is obtained (opt-in vs opt-out). In this case, both options can be used, i.e. in the case of an opt-out the coins of anyone who has not explicitly refused to donate them will be moved after the expiration of the timeout, or that timeout period could be set by default to infinity effectively meaning that the coins should never be moved. That would be the opt-in option, i.e. only the coins of those who have given explicit consent will be donated. Instead of donating coins might be marked as unmined
If you really want to make this happen, since it seems you are interested in this idea,
then it will need to be implemented under the current protocol by using a multi-sig address
and with other parties with keys, who you will trust to only move your coins after it has been
confirmed you are dead and then they will donate them or whatever based upon your wishes.
But currently that is the only way. Otherwise there will need to be direct protocol changes that
allow address contents to be "taken back" after certain requirements are met. Personally I would
not agree with such changes to be placed directly into the protocol because such a thing would allow
possible exploits to take others coins. The issue with this proposition is, you are asking the miners to
be able to not only verify transactions and build blocks, but also the power to take away bitcoins or
in theory move other user's bitcoins. This should never be allowed, is anti-Bitcoin, is against the social
contract, is against the design of the game theory system, and just plain asking for trouble.
So I'm pretty confident this path will never occur. But you could still create a secondary layer on top
of the Bitcoin network or use a thirdparty website to facilitate your idea, without directly changing the
Bitcoin protocol.
This mindset contradicts one of the reasons why Satoshi created Bitcoin in the first place.
Your money is your money and in theory, no one can take it away under any circumstances.
Comparing what regulated banks are allowed to do should not be applied to Bitcoin ever.
Shrouds have no pockets
True, but if that is your concern, then creating a multi-sig address and setting up your Estate and Will
properly should alleviate any issues that your coins will be "lost". In theory, you could donate them away
through your Will that your estate executor is obligated to perform.
A direct protocol change to add in the ability as you are suggesting is possibility way more controversial
than the blocksize limit debate. I personally believe both sides of that debate would agree not to do this.