Connectivity between African cities is relatively poor and would often involve a connecting rather than a non stop flight. JNB is obviously very poorly placed in this regard with Addis being better though still not ideal. Back in the 1980s a connecting flight via a European hub was sometimes the most practical way to fly between two African cities.
Addis Ababa is reasonably well placed for international connections into Africa, particularly from China and the Far East, and could prove a reasonable alternative to Dubai as a transfer point on some long haul routes.
Ethopian Airlines doesn't appear to suffer from the same level of corruption and government interference as South African Airways and has a long history of making profits. The company is competently managed and has in house training and maintenance to a high standard.
The main hold back is the state of the airport in Addis, but once this has been addressed, the future looks bright. At one time you would avoid flying on any middle easter airline, but now they dominate. Negative perceptions of African airlines need to be overcome but if they keep up the good work they may well succeed.