Unfortunately, all these species are only names on a wishlist Monarto supposedly has, no concrete plans. I heard of -
Sable Antelope
Greater Kudu
Impala
Okapi (This was odd considering this species isn't suited to Wild Africa)
If I had to guess Monarto wants to bolster its species count in Wild Africa and put more species behind the 'paywall'. This is odd considering that both Kudu and Sable antelope don't form large herds (rarely exceeding 20 individuals), whereas Monarto has stated it wants, "vast herds". tbh though none of the species on the import list are major herders, with the ability to form the 75+ herds Monarto wants. Monarto's Director did travel to South Africa last year for a research trip with a few staff, so if I were to guess a South African species (kudu) would be the most likely addition to Wild Africa.
If I had to guess Okapi is probably a remnant of old plans ZoosSA might have sketched up with Taronga on a joint Okapi import (considering Taronga's Congo plans). Surprising to see how far those plans got if that's the case.