The United States has a system in place which allows it to be an effective multi-cultural country, despite the massive levels of crime, constant tensions and outright hostilities that are always involved when different cultural, ethnic and religious groups live within the same national borders. They possess the world's most militarized police force, harsh laws, all-powerful security agencies, etc. which prevent the collapse of the society from inner conflict.
Looking at Sweden's system and the way things are developing, I think they might want to look towards the United States for a template that they can use to control a multi-cultural population, on a long-term basis. After all. the United States has been around as a multi-cultural country for more than a century, while Sweden is experiencing difficulties only 2 decades into their run (while still possessing an 80+% ethnic majority).
During the era of segregation and pre-Civil Rights Act, the United States experienced no greater level of crime compared to most (culturally homogenous) European countries, when different ethnic groups were kept separate from each other. For the past couple of decades, they've been able to stabilize the situation by introducing longer jail-terms, increasingly militarized police, more extensive surveillance, etc. That's basically what it takes to run a multi-cultural state. You must decrease the rights of the individual in order to control the collective.
