I think this is the difficult step. How does an attorney know whether you are incapacitated? Do they video-call you every day, and check that you aren't under duress or being deepfaked? Do they check government records of deaths every year?
It would seem that any system with a reasonable cost and reasonable latency will have to involve software at some stage, so saying "get an attorney" really means "don't trust software you've written yourself, get an attorney to write it instead".
(Okay, the attorney would pay someone else to write the software they use, but in any case, suggesting reliance on an attorney leaves unanswered the technically interesting part of the question, and doesn't really allow us to speculate about what role would actually be left to the attorney).