I've never liked Diamantidis, and I wouldn't pick him over Kidd and Nash. And if we're talking European Superstars, difference makers in the NBA. I'm afraid Dirk is first before Parker. And that's it. Gasols are good stars/sidekicks, but they ain't nothing special. Drazen was pretty good too, but no Point Guard. He played SG.
And if we're talking about amassing talent in Germany, I just don't see it happen unless rules are changed drastically to favor Europeans more. Big reason the Balkan countries and Spain produce so much talent is because it offers a way better perspective compared to other countries. Having a youth unemployment problem like these countries you faster put a big emphasis on developing your athletic capacities if you're not one of the brightest kids at school.
Unemployment rates would be one of the last parameters for me when looking at the basketball potential of a country.