Eg if you give the paper wallet to a lawyer, to pass on, how can you stop them spending it....and they just run off.
The key can be split into multiple parts, so the family receives one part and the trustee/attorney another:
pybtcsplit - m-of-n Private Key Splitting made easy in one simple python utility -
http://bt.irlbtc.com/view/104086.0What many are waiting anxiously for is the inclusion of encrypted paper wallets. So the trustee/attorney gets the decryption password and the family receives the encrypted paper wallets:
From another thread:
So the encrypted paper wallet(s) go to family members. DeadMansSwitch gets the decryption key, as does the trustee. From another thread:
I changed the colour to blue for encrypted paper wallets to provide distinction between encrypted/unencrypted paper wallets - a version in the original yellow is included in case you really like yellow, just delete 'note_encrypted.png' and rename 'note_yellow.png' in its place.

This solution (encrypted paper wallets) probably isn't ready for prime time, but give it a few weeks and that will probably become a very good method for offline long term savings that is secure.
And apparently a commercial paper wallet product (based on an open source tool) is now available with this:
now in beta as part of OpenPaperWallet (and the retail kit, SafePaperWallet) -
BIP0038 compliant, encrypted private keys in QR codes.
Software v3 BETA
The new v3 offers many features:
- A step-by-step wizard
- Multiple background design options
- Encrypted private keys (BIP0038) and in-browser decryption.
- Deterministic Aliases
https://safepaperwallet.com/software-v3-beta/