I thought the idea was that all the non-white citizens would be officially registered to the diminutive 'homelands', they'd actually be living all over the place, as would be necessary to properly exploit them. The grand vision was only that they'd live in 'homelands' and commute to work outside every day. Only very unlucky wealthy whites would have to give up land, and they'd be compensated.
That was the main tension there. 'Should we get rid of them or enslave them'? Nasty business.
Sort of, if one assigns a certain degree of ideological commitment to the architects of apartheid then the intent of the homelands was to be actually functioning environments, under Pretoria's auspices of course, that could absorb the Black populations. There was also talks of trying to get some of the neighboring Black countries, like Botswana, to take land and a bunch of people from South Africa.
I don't think the massive dependence on Black labor, to the point of large populations of Black people living outside their Bantustans, was part of the original vision. Certainly there was some expectation of some Black people remaining in the reduced South Africa, as one can see if they look at the demographic projections drawn up at the time.
There'd be more than a few Whites that would have to be compensated, you can see the map of the Bantustans here, they're so disjointed because there was a lot of prime real estate that Pretoria didn't want to either take, or purchase and give away.