The idea of defunding or disbanding is not the same as moving to a world without police. It reflects a conclusion that some cities may draw that the current arrangement is beyond reform: "rotten barrel" as opposed to "rotten apples"
So you get rid of the whole barrel and start over with something different.
In the field of education, charter schools represent an effort to do an end-run against entrenched interests. Something similar will likely emerge with respect to policing. It's not going to be easy at all. There is no magic wand out there.