Not sure you can blame it entirely on quotas. The only batsmen that were lost is rossouw and van Zyl, not sure either would make a major difference.I may be way off base here, but would you say racial issues are having an influence on any decline, perceived or real? With quotas and so many players leaving for Kolpak jobs or just giving up because they feel discriminated against? Or because they're just being realistic. Sort of like a slower, more protracted version of the exodus suffered by Zimbabwe back in the early 2000s. We saw signs of it over a decade ago with KP.
Or are people just less interested in cricket
The problem at the moment is at the franchise level. Some mediocre players blocking more talented youngsters so they develop later.
Markram is the big hope for me but he is having to learn on the job as he only had one full season of franchise cricket. He will be fine long term.