They aren't going to solve it because it would involve reworking the Blacklist system and Account IDs again. Ignoring the fact that this wouldn't get rid of all of the data that has already been obtained, they would have to make Account IDs invisible to the client and use a different system for Blacklisting which is more resource intensive on the server.
They would also have to re-fix Free Trial Accounts not being able to have mail sent to them after each Maintenance ends (Or preferably make it possible to send care packages to your free trial friends legit...) since Trial Status was linked to Account ID in Dawntrail.
And if they do make it that people you've blacklisted can't see you, like Sugar reccomended them to do, that still won't stop people from being able to see their presence in the world with third party tools. Because that already happens now, if you have someone blacklisted they still show up in a popular glamouring tool's player radar.
Your Account ID cannot be linked back to you in any way. The only way that your characters can be linked back to your personal identity is if you have already posted them online in a way that is tied to your IRL identity.