I have mixed emotions about this.
From a security professional perspective, this is at least somewhat of an improvement, even if the entire thing feels like it's held together with a wish and a prayer. I would really like if there were a means to just institute an entirely new system. Essentially having one's entire life ruined, on the chance a bad actor can guess a four digit number is...not great.
From a genealogist perspective though, this is horrible news. Being able to trackdown people based off of rough geographic assumptions can help narrow down if someone is "lucky" enough to have a common name in a specific region. Of course, this change to SSN isn't nearly as disastrous as the death of paper - especially newspapers - but I really do not envy anyone who is going to try and do historical family research in two to three hundred years. It makes me cringe just to think about how much valuable information, how many life changing moments, are going to be lost to encryption, bit rot, and the constantly changing standards of software and hardware.