At which point exactly does a state lose it's monopoly on violence, and at which point does the repression of vigilanties excuse faillure.
Never. If a state loses its monopoly on violence, it is no longer a functioning state. Order must be kept at all times by the state, not by civilian guardsmen.

Things are good here, but this really has to stop at some point, I say just disregarding the police and let racial tensions explode is a good thing.
Who will be held accountable for those deaths, then? Do we want entire mobs to storm the Bijlmer, throwing children off rooftops and things like that? I don't know what exactly you have in mind, but ethnic violence generally isn't good.

This got to go wrong at some point. A few pretty horrifying 'incidents' and some pretty harsh words
The irony of your use of the apostrophe does not elude me. What do you mean by 'incidents'? Are you suggesting that the Dutch state somehow is responsible for ...what exactly? What 'incidents' and 'harsh words' are you talking about?