In a sense we already do have gangs and different militias in control, we call them nation states. The police and army are part of that. If we dismantle the system they operate in then yes something similar will take its place, maybe private armies defending communities? Guild communities based on talents and skills something similar to early renaissance europe or the so called Dark ages. We can never fully do away with a governing organisation because without it we would not be organised. The best outcome we can hope is an efficient automated governing organisation without the class privileged rulers. This can be done through blockchain technology and volunteerism, The theory has been laid down by the Anarchist thinkers such as Kropotkin for a long time but never tried out. The best we as individuals can hope for is a community we trust, the rest is propaganda.....