As stated, American has expressed interest in flying to South Africa (both CPT and JNB) from Miami, but there are logistical issues and using a 772 just wouldn't make the profits.
It's not all logistical either, a lot of it is legal hassle.
Pilot stipulations (which should soon, if not already, no longer be a factor) and FAA refusal to grant ETOPS180 for the route play a big
SA)">DL has experimented and flown their 777 ATL-JNB.
They flew it there to demonstrate on behalf of Boeing (as well as for a possible lease) with somewhat embarrassing results.
They flew it again for a golf tournament charter.
That's about it.
Currently, the 343-600 SA is using on the ATL trip requires a stop in both directions.
It doesn't require
an eastbound stop per se, SA
chooses to stop so that they can pack on greater payload upon departure.
Even if AA stopped at DKR with their 772, they couldn't do it?L
could technically do it nonstop to CPT
with a 656K 777-223ER....
...problem is, they'd need ETOPS180 to have any chance of doing so with any decent loads, and their requests have thusfar only been obliged with an ETOPS138 allotment.
Also, there were stipluations regarding rest areas in their 772ERs (as well as other factors) for flights of that length in their pilot contract.