This is underappreciated. It's hard to seriously change organizations in less than a decade when employees have long tenures.
Opinions and behaviors are only truly malleable at the beginning of careers, and later change is fighting against the inertia of old timers' "Let me tell you how it's done."
Which isn't only negative. Esprit de corps is what holds together people doing tough jobs for long careers.
But if you want to say "No more of that. Now we're doing this" then a rebuild isn't a bad idea.
A simple first step would be to maintain a national level open registry of fired cops and bad behavior reports. At minimum, if a cop gets fired, then he can't go to the next county and get a job
This is the kind of baby steps solution that is completely not the answer even if it's part of a solution for one of the problems. This is systemic and with strong opposing forces (current police officers and their unions, as one example), you can't believe that a database of bad cops would be enough if they aren't even being fired for the abuses being committed right now, if there is already a system of protecting bad police officers why do you believe that they simply wouldn't fire or prosecute even less abuses to avoid a harsher punishment?
I've not researched enough to delineate a step-by-step process of dissolution of the police but there are enough parallels in history and similar experiences to be studied.
The little I've read about seem to include that previous police officers can re-apply but would need to go through the new revamped hiring process. Such hiring process would be defined by citizens' organisations, experts, human rights organisations and so on. There is enough scientific knowledge in that, there are enough police services in the world that use them, it's a matter of shaking the status quo and removing the old roots that US policing stems from.
This can't be achieved by steps if the roots of it are deeply rotten, you gotta understand that.
All cops nationally would be required to have a license from this organization in order to do some "reserved acts", like arresting someone, using force, firing a taser, etc. Any complaint about cops would be evaluated by this organization, and could result in the suspension / revocation of their license. There would be a strong emphasis on deontology, and the organization's explicit mission would be to protect the public.
This would probably have a similar effect overall to what you're describing, but it'd be more of a whitelist than a blacklist.
That's not necessarily a bad thing! A big problem with existing departments is decades of corruption, poor leadership, and entrenched policies. Tearing the department down and rebuilding it from scratch—even if you end up with a similar size as before—gives you the opportunity to remove the excesses/abuse. You can also do things like hiring more specialized positions and firing all the bad officers (because if the department is gone, the union can't protect them).