The stop in Dakar is probably nessesary for their business case for the route as Im sure they are concerned with SAA's response- at least they can serve a secondary market if the JNB route gets very competitive. Interestingly they have also applied for traffic rights for Dakar Joburg- not shy they chaps! that should become a nice little political squabble!
The one good spin off is that the whole DL thing as got old airways park into gear, the whole US stratergy has been reviewed- all sorts of analysis being done, MIA, ORD, even LAX. SAA has 3 gateways of its choosing into the US, the only one that will definitely stay is JFK, IAD may survive the chop initially in an attempt not to change everything at the same time.