I believe that if segregation (and it still are placed that practice it to this day) and racism acts were punished extensively for these acts they would probably refrain form doing them. Most people understand that the actions will probably be pushed under the table, so they continue to happen. These punishments should across the board not just for racism toward minorities.
It would benefit racial minorities for separatism, in terms of methods of segregation, to become explicitly outlawed and punishable by extended prison time or death. If separatism, in terms of methods of segregation were to become explicitly outlawed and punishable by extended prison time or death, then there would be a much lower possibility of segregation to occur.
The idea of death or legal punishment goes against free speech. Segregation should never be allowed or encouraged by the government, and should be discouraged by society, but people do have a right to an opinion and to keep to themselves if they wish. It would not benefit minorities anyway. Malcolm X was, at one point, for separation to preserve and better black people. Some Native tribes encourage separation because there are so few of them left, but forced separation is wrong and it's best, in my opinion, when cultures blend and mix.
Segregationists and separatists are misguided in their motivations. If these people spent just as much energy studying something worthwhile like chemistry instead of whatever races they wish to oppress and finding reasons to validate themselves, we may have found a new energy source or a cure for cancer. Instead, people find new reasons to hate each other.
We cannot shut out ears and throw racists away under lock and key, we must prevent racism by having an open and honest discussion about it as a society. We need to first acknowledge our capability of racism, then realize why we do it, and then learn to accept one another. Violence begets violence.