I'm not changing the "argument". "Succeeded" is rather ambigous. I took it to mean those high schoolers who at minimum got an NBA tryout.
The discussion for/against the NBA age limit argument (which is what this thread is about) concern the kids who have the talent to get into the NBA out of high school, so it doesn't really seem pertinent to consider those who didn't even get a tryout.
Steve Kerr's argument didn't center around those kids who didn't get drafted, and I've never heard Barkley talk about the Lenny Cooke's of the world. They are addressing the maturity/well being/bussiness aspect of high schoolers/one-and-done's who get into the NBA, not the ones who don't get a chance to play in the NBA. I'm not sure why you are bringing the latter into the discussion.
I've also never heard Steve Kerr or Barkley were talk about the NBA losing a lawsuit because of your reason below:
The NBA on its own might not let high school kids back in, but they could always be sued and forced into some kind of deal. Given that a number of kids coming directly from high-school have been successful in the NBA, it could be tricky to defend that policy in court.
In fact Kerr said the exact opposite in the article: "Regardless, it shouldn't be the NBA's responsibility to provide working opportunities for teenagers, just like it's not the NFL's responsibility to do so. The NBA should only care about running its operation the best it can. That's it."
You're the one who said the NBA would lose a lawsuit because of how successful prep to pro players have been, you then linked to a list which doesn't tell the whole story and now have tried to use some circular logic to change the conversation away from your original point.