I think this is an ideal solution; HOWEVER, I don't see it coming to fruition any time soon. This is because; 1. The amount of time to make bullioncoin fully acceptable in the marketplace. and 2. The amount of time for the public to become confident in the integrity and security of the vaulting operation.
Goldmoney is just starting to get to that point and they have a 20 year track record. Goldmoney is a similar operation without the crypto, they let you spend your gold in fiat via a mastercard.