Thats correct, one password change on the Steemit GUI will now change all four keys. A user may manage each of the four keys outside of Steemit or using his/her password manager, such as Last Pass. Combined with 'Compromised Account Recovery', the single 'Change Password' is a balance between secure key management and usability. We'll be publishing and pinning more info on Steemit GUI's security and password manager in a post.