This misses the point. The fact that most test cricketers come from a small group of elite schools is a huge part of the problem - it's not an excuse or justification for why there has been a dearth of black cricketers.
That most cricketers come from a small group of schools indicates that little progress has been made to dismantle the systems apartheid put up. The fact that black cricketers struggle to make the transition from school/provincial cricket is linked very strongly to the fact that the identification of talented teenagers predominantly takes place at a handful of elite schools, while players from non-traditional areas have to be outrageously talented to get the same attention.
I think that is a big motivation behind CSA's quotas. It will hopefully force franchises to cast their nets wider and start to identify and develop players who aren't from the same elite (often very white) recruitment areas that they've always focussed on.
If you do get large participation in grassroots cricket, common sense would dictate that you will get cohorts of black cricketers coming through. You just need to start nurturing them at higher levels rather than ignoring them and pretending a problem doesn't exist.
It doesn't come from a small dearth of schools. It is actually quite a number of schools.
Then there are these guys who are playing Proteas cricket, SA 'A' cricket, franchise cricket that didn't go to the cricketing schools and it didn't stop them.
Dale Steyn/Eldred Hawken (Merensky), Dean Elgar (St Dominics) , Stiaan Van Zyl (Boland Landbou), Vernon Philander (Ravensmead), George Linde/Beuran Hendricks (Belville), Dane Paterason (Brackenfell), JP Duminy/Rory Kleinveldt (Plumstead), Christiaan Jonker (Bergsig), Anrich Nortje (Brandwag), Yaseen Vallie (Cravenby), Clyde Fortuin (St Josephs), Basheer Walters (Nasruddin), Lesiba Ngoepe (Hans Moore), Tladi Bokako (Motherwell), Lizaad Williams (Hugenote), Rabian Engelbrecht/Keegan Petersen (New Orleans), Marchant De Lange (Ben Vorster), Dillon Du Preez/Tshepo Ntuli (Louis Botha) Luthando Mnyanda (Sea Point) , Nicky Van den Bergh/Wihann Lubbe (Potch Gym) , Dwaine Pretorius (Rustenburg), Magaliso Mosehle (Dr Johan Jurgens), Eddie Leie (Potch Boys), Sean Jamison (Veritas) , David Wiese (Witbank), Albie/Morne Morkel (Vereeniging), Henry Davids (Stellenbosch), Qaasim Adams (Tafelberg), Farhaan Behardien (Westerford), Rowan Richards (John Bisseker), Junior Dala (Springs)
Many other examples.
None of those are the elite cricket schools. They are below and quite a few of them 'white minority' now.
Boland : Paarl Boys, Paul Roos, Paarl Gym
WP : Rondebosch, Wynberg, SACS, Bishops
EP : Grey , St Andrews, Woodridge , Graeme, Kingswood
Border : Queens, Selborne, Dale, Hudson Park
KZN C : DHS, Westville, Glenwood, Kearsney, Northwood , Clifton
KZN I : Maritzburg, Hilton, Michaelhouse, St Charles
FS : Grey, St Andrews
NC : Noordkaap
GAU : KES, St Stithians, St Johns, St Davids, Jeppe , Parktown
NOR : Affies, Waterkloof, Pretoria Boys, St Albans, Centurion, Menlopark
Reason they fall off is that they just not as good when it coems to the crunch for selection higher up and that comes from the base of development cricket. But in saying that, the majority of the cricketing world would love for all their people to be open to cricket but the truth is they are not but CSA are finally waking up and realising the only way they can increase development and create better skills is academies from a young age in the more disadvantaged areas.