What type of rights does AA have on these domestic routes though? From a oneworld perspective, for example, could a BA passenger connect in GRU onto an AA flight to GIG? I think GOL is still a useful addition to AAdvantage.

I agree with you about Africa. Who would be the best candidate for African coverage? Ethiopian? To be honest, Star Alliance is not strong in Africa either. Admittedly, they have Egypt Air and SAA. However, JNB is likely too far south to be a suitable hub from most points. SkyTeam probably has the best African presence of all of the alliances with DL providing service from North America, AF/KL/KQ from Europe and KQ from Asia. KQ's NBO hub is also located in a good spot for a hub.