I'm not too worried. Even assuming that a)the conditions and organized crime of places like Rio become widespread and b) that the criminal organization eventually triumph over the state, both of which are exceedingly unlikely, the criminal organizations will find themselves in the same position as governments a few hundred years ago. The use of naked force for power only works up to a point. Eventually, people start making demands like rights, justice and the rule of law, which must in time be granted. So these criminal groups, if they somehow took power, would very quickly be forced to start acting like a somewhat legitimate government, or else face general opposition which would threaten their rule.
Whoever becomes the state, whether they are criminals, theocrats, artists or anything in between, takes on the characteristics of the state.