I could agree on foreigner limits. The rest, you're way off man. So were Spanish, Greek, Lithuanian, Serbian/Yugoslavian, Russian people freaks of athletes? They all had their share of dominating European Basketball.
Germany has everything to be one of the best Basketball country of Europe, 80+ freaking million people with a pretty good height average, one of the best economy of the world, young immigrants from everywhere(not only Turkish or middle eastern people that are weak races as you appear to think like), great great facilities, very high sport culture, crazy good organization skills(Alba Berlin have much more fans watching their team than the sum of 4 top Turkish basketball clubs) and the German discipline.
And basketball is much more than compiling athletic bodies.
On a European level sure. But NBA level? That's a whole different thing. There's very few athletes whose game translates well to the more physical, athletic NBA game. I see the point, but putting it into perspective and trying to not be offensive: There's a whole other avg level of "wealth" in Germany. So at this point it's really not desirable to pursue a pro career if you're an educated person from a financial standpoint.
And no I don't think they're weak races...I'd never say such a thing. But their physique doesn't translate outside the FIBA game to well. That's been well covered by scientists, why Western African "genes" are best for playing basketball and winning 100m sprints and Eastern African won't give other ethnics a chance to win a marathon
That combination of dedication and skill combined with size is what made Nowitzki's and Schrempf's careers. But I don't see too many of these "unique" kids coming out. Even in America there's very few of these talented, skilled large sized talents.