There's a sight I've never wanted to see again. Unless the Chinese think that an investment in clearing the Sudd for rice has a good prospect of returns, it won't happen; I expect they know about the Groundnut Scheme. Best to just concentrate on all the oil under it, I'd say.A lot of the continent is unusable for agriculture unless you're Israeli. Lack of infrastructure is also a major problem.
The wetlands in South Sudan around the Nile are huge and would likely produce all the rice the continent would need but there's no way to transport it and no will to address the issue.