@jpgoldberg Also, please keep in mind that you are basing all your estimates on how long it would take to crack passwords based on currently available hardware and currently know algorithms. But already there is talk of quantum computers that will be far faster than today's computers. What may (or may not) may be a true estimate of the time it would take to crack a password vault today might look ridiculous in five, ten, or twenty years. But in any case, people should have the ability to store their passwords locally and not be forced to trust anyone's cloud storage.
There was a time padlocks were considered pretty secure, until criminals discovered how to make lock-picking tools! But they still couldn't pick the padlock they didn't know existed.