Not exactly the same, but I've been thinking of getting a BTC denominated life insurance policy.

Its a whole-life policy and roughly the terms are pay 10 BTC in over 10 years - and receive 15 BTC at death.

The big draw of these types of arrangements is that you can borrow against the policy and pay no capital gains. So suppose that by year 5 the cash value (how much you've paid in) is at 5 BTC...this means you can borrow that 5 BTC (sell it or whatever) and then that loan gets deducted from the death benefit when you die (ie. so at death your estate receives 10 BTC payout not 15)

Obviously you need to trust the insurer...which I'm not totally sure I do. Not because I think they are shady, but simply will any company be around in 30 years? Will it even be possible for them to generate 15 BTC from my 10 BTC in "investments"....I dont know....but in theory its a solid approach.