A spouse beneficiary inherits the HSA as their own and can still use your receipts. A non-spouse beneficiary cannot — the account becomes taxable income to them.
This is the real risk in the shoebox strategy, and it comes down to who you named as beneficiary.
Spouse as beneficiary: the HSA becomes their HSA. It keeps its tax treatment, and your accumulated qualified expenses remain reimbursable. The strategy survives intact.
Non-spouse beneficiary (child, sibling, anyone else): the account stops being an HSA on the date of death. The full fair market value becomes taxable income to the beneficiary in that year. One exception: expenses you incurred before death and that are paid within 12 months of death can reduce that taxable amount — which is precisely where organized receipts matter, because someone else has to find and use them under a one-year deadline.
Estate as beneficiary: the value is included on your final return.
Two implications: name a beneficiary explicitly rather than defaulting to the estate, and make sure someone else can actually access your receipt records. A vault nobody can log into is a vault that fails at the moment it's needed.