The prevailing understanding of Khoe (loosely defined as pastoralist) and San (not always the best term, hunters, covering a very wide range of people) interactions is that they tended to absorb over time into Bantu-speaking societies and form new amalgams. For example, when Dutch trekboers expanded into the Zuurveld, they found a very dynamic and syncretic society (amaGona, usually) at the leading edge of a larger range of other syncretic societies (amaXhosa broadly, but widely variable from amaGqununkhwebe to amaMpondo). The survival of Khoesan names, grammar (including the clicks), and so forth indicate the prevalence of absorption as a mechanism. It wasn't an absorption of equals--Khoesan probably came in smaller groups, in supplication, to the more stable agripastoralist societies at certain times--but it was not quite the conflict one might suspect.

It's worth pointing out that no 'land grab' was really necessary in that instance; authority and community, if merging or dynamically evolving, would dictate the disposition of land. There was after all plenty of land before the expansion of colonization during the British period. In fact isiXhosa-speakers initially had believed they'd absorb the trekboers through these mechanisms as well in the late 1700s--the newcomers weren't numerous, they were spread out, and clearly were interested in some kind of interaction on a much higher level than independent pastoralists or hunters were. Eventually, so the reasoning went, the isolated people would fall on hard times and enter the clientage system and the communities of Bantu-speaking people. Indeed this entry to clientage did happen, even if it didn't involve intermarriage. There is some evidence, per George Stow and others, of some Khoesan hunters surviving between the clustered villages of homesteads on the Eastern Cape as well into the late 19th century--which would have extinguished their spaces because of compression in the face of colonial dispossession. Those things suggest strongly that this was not a displacing or dispossessing process, and southern Africa certainly had enough land for people to move. Khoesan-speakers, whether hunters or herders, had toolkits that were suited to the eastern half of the subcontinent, so they still monopolized it when Europeans set up shop at the Cape.

There's a fair bit we don't understand about the dynamic between the ironworking mixed farmers and the hunter/herders in the region, but that tends to be the prevalent reading--a co-evolutionary process. See chapters 2 to 4 in the new Cambridge History of South Africa (2009) which goes over the most recent literature and interpretations on it.