The time bomb here is a practical one. Stating that the land should be given back is oversimplifying a extremely complex and contentious issue.
Fact is - we have a population of 53 Million we need to feed using land that is mostly fit for grazing by sheep and goats. Only a small percentage of land in south Africa is fit for intensive agriculture and that number is going to change radically due to climate change. The question is not whether it should be given back - its whether the land will be used.
Zimbabwe has a population of 14 million and went from a top food producer, to a major importer.
As for giving productive farmland back to its original owners - the support and follow through by the state is lacking. I know of two success stories - both cases where it took the owners hard work and dedication. I know of too many cases that failed, in a lot of cases due to a lack of support from the government afterwards. And in a lot of cases the claimants are not interested in farming, and would rather receive financial restitution.