The issue is that police will not know what will no longer be a crime in the future.
You might think "well, real crimes have victims, victimless crimes don't count"
It's not that simple, for example, if the age of consent changes, then a lot of cops are now criminals, heck, even modifying it so that sexual activity is alright so long as the individuals involved are within a certain age range of each other is enough to get the cops in trouble.
heck, If the laws of free speech in the constitution are taken as they were written, than any cop who punishes someone who spams online, issues threats or incitement to criminal activity, commits hate speech, lies about their product/service, posts slander/libel, or watches/downloads/posts child porn is now innocent (assuming these examples have this as their sole offense). I'm sure that last crime is going to be of hot debate regarding it's viability, does the first amendment completely prohibit the government from regulating speech/expression/media/information? or are there "reasonable" limits to "shall not be infringed"?
What about other crimes that might be changed in the future, what qualifies as "stalking' or "harassment" is likely to change, a lot of people are going to go unprotected.
This measure will dissuade people from joining up with the police, it will make a lot f people angry that their daddy got hauled off to jail for doing his job, and it will also put a lot of people in a position where they are in a lose-lose situation, enforce the law and possibly face jailtime when it changes, refuse and you might be fired or otherwise punished for failing to do the duty you are being compensated for doing.
The police are soulless golems for a reason, it takes a specific personality type and a set of guarantees from accountability to make anyone do this kind of job.
The alternative is vigilante justice, or private police forces, both of which have a spotted past of times that they worked out better then police and time where they worked out worse than police.
Vigilantes can turn into murderers or mobs, often unintentionally (this isnt the comic books where some weird changes to human biology allow you to reliably knock someone out without killing them or doing permanent damage that may leave the victim desiring death, and not everyone is a super sleuth who is always right about the perpetrators and victims of a situation, or even if a crime occurred at all, many cases are so confusing that not even a super sleuth could be capable of have any certainty about what has happened or what was going on).
Private police forces are good, until they become mercenary forces that enforce any law by any methods that whoever is paying them wants, they will clash with each other, and the one with the most money is likely to win out, the result could be a situation like warring feudal states, or various balkanized dictatorships vying for power under "unification".
It does not take the eradication of the police to arrive at either of these scenarios, the police just need to be weak enough that trust in their ability to do what is expected of them is so low that people think they need a supplementary force to make up the difference.
I'm a hopeless optimist, and I think there may have been a time when the police were actually the protectors and servants of the people and upholders of law and order that they are intended to be today, but now they exist only to mindlessly follow orders and do whatever the establishment elites want from them, mostly this means serving the Jewish agenda. They aren't people anymore, they are soulless automatons lacking true sapience, they have sacrificed all individuality to be the fist of the establishment over it's people, "back the blue" is a retarded position to take, as the police have no interest in reciprocating or even acknowledging this opinion that people have of them.
Charlottesville was a wake up call, the police took the side in opposition to the law, intentionally enabling criminals to attack law-abiding citizens, even serving the lawful to the lawless on a silver platter, just to stand back and watch the innocent be brutalized.
The happening was supposed to occur at this point, where people realized that the police no longer care about their duties to the law, hat was a while ago.
the happening was also to occur when the government imposed itself on the average person's freedoms and livelihoods, nothing happened here either.
