The lesson here is simple: A polite society, is an armed society.
People who know the system isn't working for them take responsibility for their own personal safety and security. Much like the armed people who stood guard to protect their businesses during the riots. Remember, the police have no duty to protect anyone (Warren vs the District of Columbia ).
Chauvin has only been charged with third-degree murder (11-13 years) and second-degree manslaughter (3-5 years). They have to prove he intended to kill Floyd in order for the third-degree murder charge to stick. Doubt that will happen.
If it even goes to court, he'll take a plea bargain to manslaughter. The police union lawyers will drag this out until it cools down. Probably won't do more than 5 years, in protected custody away from general population. Under Minnesota Law, he's only required to serve 2/3 of the sentence so it might even be less.
The other 3 co-conspirators haven't been charged with anything. Doubt they'll be prosecuted due to the Doctrine of Qualified Immunity (Harlow v. Fitzgerald).
You don't get justice in court, only law.