I think the big problem for the police is at some stage people will have enough and vigilante action will take place. I remember being out with my children last halloween and a very large group of riders riding ridiculously (not on the pavement thankfully) but going through red lights at speed with lots of kids about ready to cross.
I don't want 14\15 years old dying in crashes for stealing bikes etc, but at the same time what they do will get worse and worse. I'm not sure what the answer is as the big danger of course in chasing is the danger to others through these people's careless driving.
As ever, the answer is not easy but the status quo cannot remain. The fact them can seemingly act with impunity is going to make things a lot worse.
Medium - long-term bike security will have to improve to make this a lot harder, short term a new police strategy is needed.