Yes, Delta's partnership with SAA ended. I was lucky enough to get one bus class award ticket on SAA last year (to use this year) by transferring AE pts to Delta. I called Delta something like 330 days before and grabbed the one seat offered on that flight. Had to pay for my spouse's ticket but it helped. The FF ticket took me from the west coast to the east coast, where I had a two day stopover to see friends, before going on to JNB.

Delta now has their own flight to JNB. However, last I checked, they did not have the full flat seats.