The positive side, if there is one, is that the police now have an opportunity to round up all these little fuckers and throw them in jail and keep them there, and seeing as, for a change, they are directly targeting the police rather than their modus operandi of preying upon other young people, the police may have a touch more motivation to do so.
Something really needs to be done to break the nihilistic culture of street gangs in London. I don't really know what solutions would work, given that the society these kids have grown up in is so broken. Legalising drugs would help I think, by taking this massive trade out of the hands of criminals, and other libertarian policies aimed at ending the state-run educational and welfare ghettos would also benefit society in the longer run, but in the meantime locking up the perpetrators of crime would at least remove some of the symptoms. Other than that, the police could hand out firearms to all shop-keepers, which I expect would reduce the incidence of looting.