Haha, this is a good point. If you're inventing The Hundred, you've probably lost perspective on what you might claim to be important - ie the fortunes of your Test side. The ODI side will stay in reasonably good health, because those T20 skills that are being prioritised can transfer, plus the effect of being world champions.
I don't know if we have a 'system', per se, or certainly it's nothing revolutionary. If we're saying the English game is limited to private schools, the NZ game isn't far off that either. Of our XI in the World Test final, only Trent went to a co-ed public school in NZ (Conway, Wagner and de Grandhomme not schooled in NZ). Latham, Williamson, Watling, Taylor and Jamieson went to all boys' public schools, Southee and Nicholls to private boys' schools. That's a pattern that won't change in this country.