Huh? There's plenty of already existing legal ways to do that. Just leave your key with your lawyer or a notary, and existing regulation about fiduciary duty handle everything just fine. You can also make normal private contracts that stipulate fiduciary duties, courts will enforce those contracts just fine.
As a technical alternative (or augmentation), you can also use a threshold secret sharing mechanism to store your keys amongst your friends and/or with companies.
Now what you can complain about is that there is no convenient way to do all of this. And that's a very legitimate complaint! Convenience is important.
However, the way to get convenience is not via regulation.
