I think Emergency Access could be done with Organisations and Collections.
A special Organisation is created as part of Bitwarden say “Emergency”. Then a collection ‘holds’ the master password in the same way any collection holds a password (the key here is that a collection does not violate the Bitwarden’s committment to never store unencypted data). Or it could just have a list of items in the owner’s vault like any other collection would so the master password is never exposed. There could even be more than one of these; my son gets access to one of my bank accounts. My daughter gets access to the other.
The owner can add users to the collection and selects a waiting period (default could be 2 weeks, shortest 1 week).
Access is only given to the collection after a user requests it and the waiting period is exceeded. The owner will receive notice and can cancel the request within the waiting period.