Interesting feedback.
I'm (hopefully) nowhere near the end of my life but I'm still interested in these issues since I do have a lot of significantly older friends who are also looking into Bitcoin. I've already gotten a few 'how can I will these' questions and, unfortunately, the small town CPA's they use have no answers.
That's an estate planning attorney question, not a CPA question.
I don't see anything about BTC that's fundamentally different from other currency - any competent estate planning attorney should be able to write a will/trust as appropriate that directs the person settling the estate to pay X to Y; whether the client wants X to be expressed as USD, BTC, or as a percentage of the residue of the estate is up to the client. If the attorney is unfamiliar with BTC, it'll probably just be easiest to express the intended gift as USD or as a % of the distributable estate, and let the executor deal with the BTC details.
Obviously, this will be a lot easier if the person(s) selected as the executor/administrator/trustee is familiar with BTC, or at least with technology generally. Alternatively, the client could suggest a helpful tech contact who could work with the fiduciary.
This will be more complicated if the client is hoping that their holdings can "fly under the radar" and avoid the possibility of taxation at death; a fiduciary who cooperates with that agenda is putting their own assets on the line, if there's actual tax due, and they don't pay it. This creates a blackmail/extortion opportunity. With the current US federal estate tax limit at $5.12M, there aren't so many people running around who need to worry about federal estate tax. Different states have estate/inheritance tax schemes, so that detail is state-specific.
With respect to BTC as an investment vehicle, I don't see how the possibility of death really changes things - either you view it as a sensible investment vehicle or you don't. The fact that the beneficial owner(s) may change doesn't seem very interesting to me, assuming the fiduciary has or can hire/arrange technical competence sufficient to manage BTC holdings.
In many ways, BTC is easier to plan for than other assets, because there's no institution to fight with or demand that forms be filled out - it's more like having an envelope of cash, except that with BTC there's a public log of all transactions, so there's no meaningful argument about how much BTC the decedent held at death. It's not so unusual for envelopes of cash or sleeves of coins to disappear from decedent's houses/safes/safe deposit boxes shortly after death, and of course nobody has any idea what happened or where those assets went. With BTC, that confusion won't be so bad, though security of the private key(s) will always be interesting. If assets disappear shortly after death, the beneficiaries will be able to see that, and demand answers from the person(s) who had access to the decedent's key(s). This will be easier if the decedent makes a list of their addresses known to the beneficiaries - if there were a decedent who had any number of key pairs, it might take a long time (up to infinity) for their successors to identify all of the BTC's and get access to the private keys.
