The far right is very small and marginalized. The AWB, of which Terreblanch had been the leader, already stated there will be no revenge attacks.
The political temperature has been rising though over the past year or two with Julius Malema (a racist buffoon in the Robert Mugabe mould) singing songs like "...kill the boer, kill the farmer" and making numerous inflammatory remarks from a public platform. Usually one ignores that kind of thing but it becomes harder if farm murders are indeed a reality and a concern for most. It may take one radical lunatic to spark something but I don't think the support for these radicals are big enough to build into sufficient momentum. The ANC has been reluctant to confront Malema but my guess is that they will now reign him in (or try to) until after the World Cup. All the parties are sensitive of the perception of SA overseas and everyone wants a successful World Cup.
There is a lot of excitement re the World Cup in SA which will no doubt still increase closer to the event itself. People there are also appreciative of an improved public transport system, highways and the other advantages of hosting the event, improvements which wouldn't have been possible without the World Cup. There is a great expectation of seeing the top teams and players in action.
There are some lingering concerns too though. Some people are still worried about the long term financial effects and whether the Cape Town stadium will become a white elephant. They are also not going to see nearly the number of visitors initially expected because of the long flight times to get there and the World just coming out of a major financial crisis. It also doesn't help that SA have a team with no hope of surviving the first round, the real excitement would have been to be able to identify with your own team's success. Fortunately SA rugby and cricket provide good alternatives.