Third Degree Murder seems appropriate to me. I could be wrong, but I think they'll convict him on that.
Minnesota's third-degree murder statute reads: "Whoever, without intent…causes the death of another by perpetrating an act eminently dangerous to others and evincing a depraved mind, without regard for human life…"
"perpetrating an act eminently dangerous to others" - the Minneapolis police are instructed to do this to subdue somebody who is resisting arrest, right? So, is it eminently dangerous to others? Eminently means 'extremely'; is it really? How many others have died from a knee to the neck vs how many didn't? Would Floyd have died if he didn't have that Fentenyl in his body? Absent that condition was the action Chauvin took extremely dangerous to others?
"evincing a depraved mind, without regard for human life…" - how the hell do you prove that in a court of law? Chauvin was performing his duty according to his training, was he not? How are you going to show a 'depraved mind' when his training told him to do it?
All that said, an argument could be made that Chauvin should have taken his knee off Floyd's neck sooner than he did. I don't know the correct term for that misconduct, but I don't think he is guilty of 3rd degree murder.