Quotas, targets, or whatever you want to call them, will not achieve anything in the top tiers of the game. They cannot, because this type of approach is always doomed to failure, firstly by disaffecting more highly talented players who will just leave the country for work, and secondly by chucking sub-standard players in at the deep end. I can think of a least a few players in the current Springbok squad who are quite simply, not only not good enough for Springbok duty, but whom would not even merit selection for any Mitre10 cup side - Trevor Nykane, Bongi Mbonambi, Rudy Paige and Teboho Mohoje.
The correct, and IMO, only way to increase the number of black players and players of colour at the top of the pyramid, is to increase the number at the bottom. You start by offering the opportunities with funding and coaching clinics at school level, right from early on (5 & 6 yo). However, you can only offer this; players have to decide for themselves if they want to play the game. In NZ we have something called "Rippa rugby" – a variation of tag rugby which is played in Australia, Ireland, UK and the USA. Its used as a developmental game for young children, and for primary/grade school tournaments.
http://www.smallblacks.com/rippa-rugby/
Early talent identification is absolutely key, and resources are targeted to players who get noticed. Funding, especially, needs to be conditional on that money being spent on rugby coaching and development, and the simple way to do that, and avoid what Heineken (IIRC) mentioned in another thread about grant money being spent on Soccer, is for the money to be allocated and held by SARU (or whoever they put in charge of youth rugby development). The schools then request what they want to spend it on, and if it is a valid resource, SARU pays for it from that school's allocation. If the school chooses not to spend it, then they get no allocation the following year, and their allocation is distributed to the allocations for other schools.
Take care of the grass roots, and the top end will mostly take care of itself. This is what we do here, and you will struggle to argue that it does not work. But most importantly, this is not a quick fix - there are in fact NO quick fixes. It will take time, and patience.